diff --git a/apps/api-extractor/src/analyzer/ExportAnalyzer.ts b/apps/api-extractor/src/analyzer/ExportAnalyzer.ts
index 09d9c70acc9..b7c9ad7ab97 100644
--- a/apps/api-extractor/src/analyzer/ExportAnalyzer.ts
+++ b/apps/api-extractor/src/analyzer/ExportAnalyzer.ts
@@ -259,11 +259,18 @@ export class ExportAnalyzer {
     importOrExportDeclaration: ts.ImportDeclaration | ts.ExportDeclaration | ts.ImportTypeNode,
     moduleSpecifier: string
   ): boolean {
-    const resolvedModule: ts.ResolvedModuleFull = this._getResolvedModule(
-      importOrExportDeclaration,
+    const resolvedModule: ts.ResolvedModuleFull | undefined = TypeScriptInternals.getResolvedModule(
+      importOrExportDeclaration.getSourceFile(),
       moduleSpecifier
     );
 
+    if (resolvedModule === undefined) {
+      // The TS compiler API `getResolvedModule` cannot resolve ambient modules. Thus, to match API Extractor's
+      // previous behavior, simply treat all ambient modules as external. This bug is tracked by
+      // https://github.com/microsoft/rushstack/issues/3335.
+      return true;
+    }
+
     // Either something like `jquery` or `@microsoft/api-extractor`.
     const packageName: string | undefined = resolvedModule.packageId?.name;
     if (packageName !== undefined && this._bundledPackageNames.has(packageName)) {
@@ -856,11 +863,23 @@ export class ExportAnalyzer {
     exportSymbol: ts.Symbol
   ): AstModule {
     const moduleSpecifier: string = this._getModuleSpecifier(importOrExportDeclaration);
-    const resolvedModule: ts.ResolvedModuleFull = this._getResolvedModule(
-      importOrExportDeclaration,
+    const resolvedModule: ts.ResolvedModuleFull | undefined = TypeScriptInternals.getResolvedModule(
+      importOrExportDeclaration.getSourceFile(),
       moduleSpecifier
     );
 
+    if (resolvedModule === undefined) {
+      // Encountered in https://github.com/microsoft/rushstack/issues/1914.
+      //
+      // It's also possible for this to occur with ambient modules. However, in practice this doesn't happen
+      // as API Extractor treats all ambient modules as external per the logic in `_isExternalModulePath`, and
+      // thus this code path is never reached for ambient modules.
+      throw new InternalError(
+        `getResolvedModule() could not resolve module name ${JSON.stringify(moduleSpecifier)}\n` +
+          SourceFileLocationFormatter.formatDeclaration(importOrExportDeclaration)
+      );
+    }
+
     // Map the filename back to the corresponding SourceFile. This circuitous approach is needed because
     // we have no way to access the compiler's internal resolveExternalModuleName() function
     const moduleSourceFile: ts.SourceFile | undefined = this._program.getSourceFile(
@@ -919,29 +938,6 @@ export class ExportAnalyzer {
     return astImport;
   }
 
-  private _getResolvedModule(
-    importOrExportDeclaration: ts.ImportDeclaration | ts.ExportDeclaration | ts.ImportTypeNode,
-    moduleSpecifier: string
-  ): ts.ResolvedModuleFull {
-    const resolvedModule: ts.ResolvedModuleFull | undefined = TypeScriptInternals.getResolvedModule(
-      importOrExportDeclaration.getSourceFile(),
-      moduleSpecifier
-    );
-
-    if (resolvedModule === undefined) {
-      // This should not happen, since getResolvedModule() specifically looks up names that the compiler
-      // found in export declarations for this source file
-      //
-      // Encountered in https://github.com/microsoft/rushstack/issues/1914
-      throw new InternalError(
-        `getResolvedModule() could not resolve module name ${JSON.stringify(moduleSpecifier)}\n` +
-          SourceFileLocationFormatter.formatDeclaration(importOrExportDeclaration)
-      );
-    }
-
-    return resolvedModule;
-  }
-
   private _getModuleSpecifier(
     importOrExportDeclaration: ts.ImportDeclaration | ts.ExportDeclaration | ts.ImportTypeNode
   ): string {
diff --git a/build-tests/api-extractor-scenarios/config/build-config.json b/build-tests/api-extractor-scenarios/config/build-config.json
index a6c0a5e7e64..dc194fe5192 100644
--- a/build-tests/api-extractor-scenarios/config/build-config.json
+++ b/build-tests/api-extractor-scenarios/config/build-config.json
@@ -34,7 +34,6 @@
     "inconsistentReleaseTags",
     "internationalCharacters",
     "namedDefaultImport",
-    "pathMappings",
     "preapproved",
     "spanSorting",
     "typeOf",
diff --git a/build-tests/api-extractor-scenarios/etc/test-outputs/pathMappings/api-extractor-scenarios.api.json b/build-tests/api-extractor-scenarios/etc/test-outputs/pathMappings/api-extractor-scenarios.api.json
deleted file mode 100644
index fddf491490f..00000000000
--- a/build-tests/api-extractor-scenarios/etc/test-outputs/pathMappings/api-extractor-scenarios.api.json
+++ /dev/null
@@ -1,448 +0,0 @@
-{
-  "metadata": {
-    "toolPackage": "@microsoft/api-extractor",
-    "toolVersion": "[test mode]",
-    "schemaVersion": 1005,
-    "oldestForwardsCompatibleVersion": 1001,
-    "tsdocConfig": {
-      "$schema": "https://developer.microsoft.com/json-schemas/tsdoc/v0/tsdoc.schema.json",
-      "noStandardTags": true,
-      "tagDefinitions": [
-        {
-          "tagName": "@alpha",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@beta",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@defaultValue",
-          "syntaxKind": "block"
-        },
-        {
-          "tagName": "@decorator",
-          "syntaxKind": "block",
-          "allowMultiple": true
-        },
-        {
-          "tagName": "@deprecated",
-          "syntaxKind": "block"
-        },
-        {
-          "tagName": "@eventProperty",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@example",
-          "syntaxKind": "block",
-          "allowMultiple": true
-        },
-        {
-          "tagName": "@experimental",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@inheritDoc",
-          "syntaxKind": "inline"
-        },
-        {
-          "tagName": "@internal",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@label",
-          "syntaxKind": "inline"
-        },
-        {
-          "tagName": "@link",
-          "syntaxKind": "inline",
-          "allowMultiple": true
-        },
-        {
-          "tagName": "@override",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@packageDocumentation",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@param",
-          "syntaxKind": "block",
-          "allowMultiple": true
-        },
-        {
-          "tagName": "@privateRemarks",
-          "syntaxKind": "block"
-        },
-        {
-          "tagName": "@public",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@readonly",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@remarks",
-          "syntaxKind": "block"
-        },
-        {
-          "tagName": "@returns",
-          "syntaxKind": "block"
-        },
-        {
-          "tagName": "@sealed",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@see",
-          "syntaxKind": "block"
-        },
-        {
-          "tagName": "@throws",
-          "syntaxKind": "block",
-          "allowMultiple": true
-        },
-        {
-          "tagName": "@typeParam",
-          "syntaxKind": "block",
-          "allowMultiple": true
-        },
-        {
-          "tagName": "@virtual",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@betaDocumentation",
-          "syntaxKind": "modifier"
-        },
-        {
-          "tagName": "@internalRemarks",
-          "syntaxKind": "block"
-        },
-        {
-          "tagName": "@preapproved",
-          "syntaxKind": "modifier"
-        }
-      ],
-      "supportForTags": {
-        "@alpha": true,
-        "@beta": true,
-        "@defaultValue": true,
-        "@decorator": true,
-        "@deprecated": true,
-        "@eventProperty": true,
-        "@example": true,
-        "@experimental": true,
-        "@inheritDoc": true,
-        "@internal": true,
-        "@label": true,
-        "@link": true,
-        "@override": true,
-        "@packageDocumentation": true,
-        "@param": true,
-        "@privateRemarks": true,
-        "@public": true,
-        "@readonly": true,
-        "@remarks": true,
-        "@returns": true,
-        "@sealed": true,
-        "@see": true,
-        "@throws": true,
-        "@typeParam": true,
-        "@virtual": true,
-        "@betaDocumentation": true,
-        "@internalRemarks": true,
-        "@preapproved": true
-      }
-    }
-  },
-  "kind": "Package",
-  "canonicalReference": "api-extractor-scenarios!",
-  "docComment": "",
-  "name": "api-extractor-scenarios",
-  "members": [
-    {
-      "kind": "EntryPoint",
-      "canonicalReference": "api-extractor-scenarios!",
-      "name": "",
-      "members": [
-        {
-          "kind": "Class",
-          "canonicalReference": "api-extractor-scenarios!AbstractClass:class",
-          "docComment": "/**\n * @public\n */\n",
-          "excerptTokens": [
-            {
-              "kind": "Content",
-              "text": "export abstract class AbstractClass "
-            }
-          ],
-          "releaseTag": "Public",
-          "name": "AbstractClass",
-          "members": [
-            {
-              "kind": "Method",
-              "canonicalReference": "api-extractor-scenarios!AbstractClass#member:member(1)",
-              "docComment": "",
-              "excerptTokens": [
-                {
-                  "kind": "Content",
-                  "text": "public abstract member(): "
-                },
-                {
-                  "kind": "Content",
-                  "text": "void"
-                },
-                {
-                  "kind": "Content",
-                  "text": ";"
-                }
-              ],
-              "isOptional": false,
-              "isStatic": false,
-              "returnTypeTokenRange": {
-                "startIndex": 1,
-                "endIndex": 2
-              },
-              "releaseTag": "Public",
-              "overloadIndex": 1,
-              "parameters": [],
-              "name": "member"
-            }
-          ],
-          "implementsTokenRanges": []
-        },
-        {
-          "kind": "Enum",
-          "canonicalReference": "api-extractor-scenarios!RegularEnum:enum",
-          "docComment": "/**\n * @public\n */\n",
-          "excerptTokens": [
-            {
-              "kind": "Content",
-              "text": "export enum RegularEnum "
-            }
-          ],
-          "releaseTag": "Public",
-          "name": "RegularEnum",
-          "members": [
-            {
-              "kind": "EnumMember",
-              "canonicalReference": "api-extractor-scenarios!RegularEnum.One:member",
-              "docComment": "/**\n * These are some docs for One\n */\n",
-              "excerptTokens": [
-                {
-                  "kind": "Content",
-                  "text": "One = "
-                },
-                {
-                  "kind": "Content",
-                  "text": "1"
-                }
-              ],
-              "releaseTag": "Public",
-              "name": "One",
-              "initializerTokenRange": {
-                "startIndex": 1,
-                "endIndex": 2
-              }
-            },
-            {
-              "kind": "EnumMember",
-              "canonicalReference": "api-extractor-scenarios!RegularEnum.Two:member",
-              "docComment": "/**\n * These are some docs for Two\n */\n",
-              "excerptTokens": [
-                {
-                  "kind": "Content",
-                  "text": "Two = "
-                },
-                {
-                  "kind": "Reference",
-                  "text": "RegularEnum.One",
-                  "canonicalReference": "api-extractor-scenarios!RegularEnum.One:member"
-                },
-                {
-                  "kind": "Content",
-                  "text": " + 1"
-                }
-              ],
-              "releaseTag": "Public",
-              "name": "Two",
-              "initializerTokenRange": {
-                "startIndex": 1,
-                "endIndex": 3
-              }
-            },
-            {
-              "kind": "EnumMember",
-              "canonicalReference": "api-extractor-scenarios!RegularEnum.Zero:member",
-              "docComment": "/**\n * These are some docs for Zero\n */\n",
-              "excerptTokens": [
-                {
-                  "kind": "Content",
-                  "text": "Zero"
-                }
-              ],
-              "releaseTag": "Public",
-              "name": "Zero",
-              "initializerTokenRange": {
-                "startIndex": 0,
-                "endIndex": 0
-              }
-            }
-          ]
-        },
-        {
-          "kind": "Class",
-          "canonicalReference": "api-extractor-scenarios!SimpleClass:class",
-          "docComment": "/**\n * @public\n */\n",
-          "excerptTokens": [
-            {
-              "kind": "Content",
-              "text": "export class SimpleClass "
-            }
-          ],
-          "releaseTag": "Public",
-          "name": "SimpleClass",
-          "members": [
-            {
-              "kind": "Method",
-              "canonicalReference": "api-extractor-scenarios!SimpleClass#member:member(1)",
-              "docComment": "",
-              "excerptTokens": [
-                {
-                  "kind": "Content",
-                  "text": "public member(): "
-                },
-                {
-                  "kind": "Content",
-                  "text": "void "
-                },
-                {
-                  "kind": "Content",
-                  "text": "{}"
-                }
-              ],
-              "isOptional": false,
-              "isStatic": false,
-              "returnTypeTokenRange": {
-                "startIndex": 1,
-                "endIndex": 2
-              },
-              "releaseTag": "Public",
-              "overloadIndex": 1,
-              "parameters": [],
-              "name": "member"
-            },
-            {
-              "kind": "Method",
-              "canonicalReference": "api-extractor-scenarios!SimpleClass#optionalParamMethod:member(1)",
-              "docComment": "",
-              "excerptTokens": [
-                {
-                  "kind": "Content",
-                  "text": "public optionalParamMethod(x?: "
-                },
-                {
-                  "kind": "Content",
-                  "text": "number"
-                },
-                {
-                  "kind": "Content",
-                  "text": "): "
-                },
-                {
-                  "kind": "Content",
-                  "text": "void "
-                },
-                {
-                  "kind": "Content",
-                  "text": "{}"
-                }
-              ],
-              "isOptional": false,
-              "isStatic": false,
-              "returnTypeTokenRange": {
-                "startIndex": 3,
-                "endIndex": 4
-              },
-              "releaseTag": "Public",
-              "overloadIndex": 1,
-              "parameters": [
-                {
-                  "parameterName": "x",
-                  "parameterTypeTokenRange": {
-                    "startIndex": 1,
-                    "endIndex": 2
-                  },
-                  "isOptional": true
-                }
-              ],
-              "name": "optionalParamMethod"
-            },
-            {
-              "kind": "Property",
-              "canonicalReference": "api-extractor-scenarios!SimpleClass#readonlyProperty:member",
-              "docComment": "",
-              "excerptTokens": [
-                {
-                  "kind": "Content",
-                  "text": "public get readonlyProperty(): "
-                },
-                {
-                  "kind": "Content",
-                  "text": "string "
-                },
-                {
-                  "kind": "Content",
-                  "text": "{\n    return 'hello';\n  }"
-                }
-              ],
-              "isOptional": false,
-              "releaseTag": "Public",
-              "name": "readonlyProperty",
-              "propertyTypeTokenRange": {
-                "startIndex": 1,
-                "endIndex": 2
-              },
-              "isStatic": false
-            },
-            {
-              "kind": "Property",
-              "canonicalReference": "api-extractor-scenarios!SimpleClass#writeableProperty:member",
-              "docComment": "",
-              "excerptTokens": [
-                {
-                  "kind": "Content",
-                  "text": "public get writeableProperty(): "
-                },
-                {
-                  "kind": "Content",
-                  "text": "string "
-                },
-                {
-                  "kind": "Content",
-                  "text": "{\n    return 'hello';\n  }"
-                },
-                {
-                  "kind": "Content",
-                  "text": "\n\npublic set writeableProperty(value: string) {}"
-                }
-              ],
-              "isOptional": false,
-              "releaseTag": "Public",
-              "name": "writeableProperty",
-              "propertyTypeTokenRange": {
-                "startIndex": 1,
-                "endIndex": 2
-              },
-              "isStatic": false
-            }
-          ],
-          "implementsTokenRanges": []
-        }
-      ]
-    }
-  ]
-}
diff --git a/build-tests/api-extractor-scenarios/etc/test-outputs/pathMappings/api-extractor-scenarios.api.md b/build-tests/api-extractor-scenarios/etc/test-outputs/pathMappings/api-extractor-scenarios.api.md
deleted file mode 100644
index a932d81a1a0..00000000000
--- a/build-tests/api-extractor-scenarios/etc/test-outputs/pathMappings/api-extractor-scenarios.api.md
+++ /dev/null
@@ -1,45 +0,0 @@
-## API Report File for "api-extractor-scenarios"
-
-> Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
-
-```ts
-
-// @public (undocumented)
-export abstract class AbstractClass {
-    // (undocumented)
-    public abstract member(): void;
-}
-
-// @public (undocumented)
-export enum RegularEnum {
-    One = 1,
-
-    Two = RegularEnum.One + 1,
-
-    Zero
-}
-
-// @public (undocumented)
-export class SimpleClass {
-    // (undocumented)
-    public member(): void {}
-
-    // (undocumented)
-    public optionalParamMethod(x?: number): void {}
-
-    // (undocumented)
-    public get readonlyProperty(): string {
-        return 'hello';
-    }
-
-    // (undocumented)
-    public get writeableProperty(): string {
-        return 'hello';
-    }
-
-    public set writeableProperty(value: string) {}
-}
-
-// (No @packageDocumentation comment for this package)
-
-```
diff --git a/build-tests/api-extractor-scenarios/etc/test-outputs/pathMappings/rollup.d.ts b/build-tests/api-extractor-scenarios/etc/test-outputs/pathMappings/rollup.d.ts
deleted file mode 100644
index d7f81f3baab..00000000000
--- a/build-tests/api-extractor-scenarios/etc/test-outputs/pathMappings/rollup.d.ts
+++ /dev/null
@@ -1,40 +0,0 @@
-/** @public */
-export declare abstract class AbstractClass {
-    public abstract member(): void;
-}
-
-/** @public */
-export declare enum RegularEnum {
-    /**
-     * These are some docs for Zero
-     */
-    Zero,
-
-    /**
-     * These are some docs for One
-     */
-    One = 1,
-
-    /**
-     * These are some docs for Two
-     */
-    Two = RegularEnum.One + 1
-}
-
-/** @public */
-export declare class SimpleClass {
-    public member(): void {}
-
-    public optionalParamMethod(x?: number): void {}
-
-    public get readonlyProperty(): string {
-        return 'hello';
-    }
-
-    public get writeableProperty(): string {
-        return 'hello';
-    }
-    public set writeableProperty(value: string) {}
-}
-
-export { }
diff --git a/build-tests/api-extractor-scenarios/src/pathMappings/index.ts b/build-tests/api-extractor-scenarios/src/pathMappings/index.ts
deleted file mode 100644
index 90683d28bd7..00000000000
--- a/build-tests/api-extractor-scenarios/src/pathMappings/index.ts
+++ /dev/null
@@ -1,9 +0,0 @@
-// Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license.
-// See LICENSE in the project root for license information.
-
-// Relies upon tsconfig `baseUrl` & `paths`.
-export { AbstractClass } from 'path-mapping';
-export { SimpleClass } from 'wildcard-path-mapping/apiItemKinds';
-
-// Relies upon only tsconfig `baseUrl`.
-export { RegularEnum } from 'src/apiItemKinds';
diff --git a/build-tests/api-extractor-scenarios/tsconfig.json b/build-tests/api-extractor-scenarios/tsconfig.json
index ced6570b1b2..1799652cc42 100644
--- a/build-tests/api-extractor-scenarios/tsconfig.json
+++ b/build-tests/api-extractor-scenarios/tsconfig.json
@@ -10,14 +10,7 @@
     "strictNullChecks": true,
     "types": ["node", "jest"],
     "lib": ["es5", "scripthost", "es2015.collection", "es2015.promise", "es2015.iterable", "dom"],
-    "outDir": "lib",
-
-    // These properties are only used by the pathMappings/ test scenario.
-    "baseUrl": ".",
-    "paths": {
-      "path-mapping": ["src/apiItemKinds"],
-      "wildcard-path-mapping/*": ["src/*"]
-    }
+    "outDir": "lib"
   },
   "include": ["src/**/*.ts", "typings/tsd.d.ts"]
 }
diff --git a/build-tests/install-test-workspace/workspace/common/pnpm-lock.yaml b/build-tests/install-test-workspace/workspace/common/pnpm-lock.yaml
index 24daa6581aa..1883010fbd5 100644
--- a/build-tests/install-test-workspace/workspace/common/pnpm-lock.yaml
+++ b/build-tests/install-test-workspace/workspace/common/pnpm-lock.yaml
@@ -5,13 +5,13 @@ importers:
   typescript-newest-test:
     specifiers:
       '@rushstack/eslint-config': file:rushstack-eslint-config-2.5.2.tgz
-      '@rushstack/heft': file:rushstack-heft-0.44.5.tgz
+      '@rushstack/heft': file:rushstack-heft-0.44.7.tgz
       eslint: ~8.7.0
       tslint: ~5.20.1
       typescript: ~4.5.2
     devDependencies:
       '@rushstack/eslint-config': file:../temp/tarballs/rushstack-eslint-config-2.5.2.tgz_eslint@8.7.0+typescript@4.5.2
-      '@rushstack/heft': file:../temp/tarballs/rushstack-heft-0.44.5.tgz
+      '@rushstack/heft': file:../temp/tarballs/rushstack-heft-0.44.7.tgz
       eslint: 8.7.0
       tslint: 5.20.1_typescript@4.5.2
       typescript: 4.5.2
@@ -19,13 +19,13 @@ importers:
   typescript-v3-test:
     specifiers:
       '@rushstack/eslint-config': file:rushstack-eslint-config-2.5.2.tgz
-      '@rushstack/heft': file:rushstack-heft-0.44.5.tgz
+      '@rushstack/heft': file:rushstack-heft-0.44.7.tgz
       eslint: ~8.7.0
       tslint: ~5.20.1
       typescript: ~4.5.2
     devDependencies:
       '@rushstack/eslint-config': file:../temp/tarballs/rushstack-eslint-config-2.5.2.tgz_eslint@8.7.0+typescript@4.5.2
-      '@rushstack/heft': file:../temp/tarballs/rushstack-heft-0.44.5.tgz
+      '@rushstack/heft': file:../temp/tarballs/rushstack-heft-0.44.7.tgz
       eslint: 8.7.0
       tslint: 5.20.1_typescript@4.5.2
       typescript: 4.5.2
@@ -1720,10 +1720,10 @@ packages:
       - typescript
     dev: true
 
-  file:../temp/tarballs/rushstack-heft-0.44.5.tgz:
-    resolution: {tarball: file:../temp/tarballs/rushstack-heft-0.44.5.tgz}
+  file:../temp/tarballs/rushstack-heft-0.44.7.tgz:
+    resolution: {tarball: file:../temp/tarballs/rushstack-heft-0.44.7.tgz}
     name: '@rushstack/heft'
-    version: 0.44.5
+    version: 0.44.7
     engines: {node: '>=10.13.0'}
     hasBin: true
     dependencies:
diff --git a/common/changes/@microsoft/api-extractor/ambient-module-fix_2022-04-09-15-19.json b/common/changes/@microsoft/api-extractor/ambient-module-fix_2022-04-09-15-19.json
new file mode 100644
index 00000000000..d78b14c2a46
--- /dev/null
+++ b/common/changes/@microsoft/api-extractor/ambient-module-fix_2022-04-09-15-19.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/api-extractor",
+      "comment": "Fix ambient modules bug caused by #3321.",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@microsoft/api-extractor"
+}
\ No newline at end of file