diff --git a/lib/BackgroundJob/OrganizationContactSyncJob.php b/lib/BackgroundJob/OrganizationContactSyncJob.php
index e22912ff..1d581cf8 100644
--- a/lib/BackgroundJob/OrganizationContactSyncJob.php
+++ b/lib/BackgroundJob/OrganizationContactSyncJob.php
@@ -94,6 +94,17 @@ protected function run($argument): void
         }
 
         $this->logger->info('[OrganizationContactSyncJob] Starting scheduled organization sync');
-        $this->orgSyncService->performScheduledSync();
+        try {
+            $this->orgSyncService->performScheduledSync();
+        } catch (\Throwable $e) {
+            $this->logger->error(
+                '[OrganizationContactSyncJob] Fatal error during sync — cron pass protected',
+                [
+                    'error' => $e->getMessage(),
+                    'file'  => $e->getFile(),
+                    'line'  => $e->getLine(),
+                ]
+            );
+        }//end try
     }//end run()
 }//end class
diff --git a/lib/Controller/ContactpersonenController.php b/lib/Controller/ContactpersonenController.php
index 31f8dd17..796741bf 100644
--- a/lib/Controller/ContactpersonenController.php
+++ b/lib/Controller/ContactpersonenController.php
@@ -671,7 +671,7 @@ public function updateUserGroups(string $username, array $groups=[]): JSONRespon
             $curCatalogGroups = [];
 
             foreach ($currentGroups as $group) {
-                if (in_array(needle: $group->getGID() === true, haystack: $allowedGroups) === true) {
+                if (in_array(needle: $group->getGID(), haystack: $allowedGroups) === true) {
                     $curCatalogGroups[] = $group->getGID();
                 }
             }
diff --git a/lib/Service/OrganizationSyncService.php b/lib/Service/OrganizationSyncService.php
index 7dd9b4ce..5640abb7 100644
--- a/lib/Service/OrganizationSyncService.php
+++ b/lib/Service/OrganizationSyncService.php
@@ -426,11 +426,9 @@ public function performContactSync(int $batchSize=100, int $maxExecutionSeconds=
                 $contactEntityObject = $contactEntity->getObject();
                 $contactEntityObject['username'] = $contact['uid'];
 
-                // Temporarily remove organisatie field to avoid validation error.
-                // (schema expects object type but field stores a UUID string).
-                $savedOrganisatie = $contactEntityObject['organisatie'] ?? null;
-                unset($contactEntityObject['organisatie']);
-
+                // Keep organisatie in the object so it is never temporarily absent from the
+                // persisted record. The schema validation warning for a UUID-string value is
+                // benign compared to a data-corruption window where the field is missing.
                 $contactEntity->setObject($contactEntityObject);
                 $objectService->saveObject(
                     object: $contactEntity,
@@ -440,15 +438,6 @@ public function performContactSync(int $batchSize=100, int $maxExecutionSeconds=
                     _multitenancy: false
                 );
 
-                // Restore the organisatie field so the link is preserved.
-                if ($savedOrganisatie !== null) {
-                    $restoredData = $contactEntity->getObject();
-                    $restoredData['organisatie'] = $savedOrganisatie;
-                    $contactEntity->setObject($restoredData);
-                    $objectMapper = \OC::$server->get('OCA\OpenRegister\Db\MagicMapper');
-                    $objectMapper->update($contactEntity);
-                }
-
                 $stats['contactPersonsProcessed']++;
             } catch (\Exception $e) {
                 $stats['errors'][] = $contact['uuid'].': '.$e->getMessage();
@@ -493,8 +482,10 @@ public function performUserSync(): array
         $platform   = $this->db->getDatabasePlatform();
         $isPostgres = $platform instanceof \Doctrine\DBAL\Platforms\PostgreSQLPlatform;
 
-            $jsonContainsCheck = "JSON_CONTAINS(oo.users, CONCAT('\"', o.username, '\"')) = 0";
         if ($isPostgres === true) {
+            $jsonContainsCheck = "NOT (oo.users::jsonb @> to_jsonb(o.username::text))";
+        } else {
+            $jsonContainsCheck = "JSON_CONTAINS(oo.users, CONCAT('\"', o.username, '\"')) = 0";
         }
 
         // Find contacts with a username whose username is NOT in their org's users array.
@@ -503,7 +494,7 @@ public function performUserSync(): array
             ->from($contactTableName, 'o')
             ->leftJoin('o', 'openregister_organisations', 'oo', 'oo.uuid = o.organisatie')
             ->where($qb->createFunction('o.username IS NOT NULL'))
-            ->andWhere($qb->createFunction('o.username !== '.$qb->createNamedParameter('')))
+            ->andWhere($qb->createFunction('o.username <> '.$qb->createNamedParameter('')))
             ->andWhere($qb->createFunction('o.organisatie IS NOT NULL'))
             ->andWhere($qb->createFunction($jsonContainsCheck));
 
@@ -2815,8 +2806,10 @@ public function performOptimizedManualSync(int $maxRounds=10, int $batchSize=100
      */
     public function performScheduledSync(int $minutesBack=0): array
     {
-            $syncModeValue = 'incremental';
         if ($minutesBack === 0) {
+            $syncModeValue = 'full';
+        } else {
+            $syncModeValue = 'incremental';
         }
 
         $this->logger->info(