Doesn't work in 2.83.4

[InconsolableCellist]

Steps to reproduce:

1. Run Blender 2.83.4 (or newer?)
2. Edit->Preferences->Install, choose the .py file from this project
3. Verify the addon is installed and enabled by searching for it. ("Helper")
4. Select and object and go to the object data properties tab in the Properties editor
5. Expand the Shake Keys section and click the Shape Key Specials arrow button

Expected results:
Three new menu entries appear from the addon

Actual results:
No new menu entries appear

During install (step 2) the only log output is:

Modules Installed (shapeKeyHelper_menu) from '/home/user/Downloads/ShapeKey-Helpers-master/shapeKeyHelper_menu.py' into '/home/user/.config/blender/2.83/scripts/addons'

Installing by just selecting the zip file also fails, just saying:

Modules Installed (shapeKeyHelper_menu) from '/home/user/Downloads/ShapeKey-Helpers-1.1/shapeKeyHelper_menu.py' into '/home/user/.config/blender/2.83/scripts/addons'

but the addon then doesn't even appear in the list of available/enabled addons

Environment:
Linux

[magnoelcabiadito]

Since i already had it installed when i upgraded from 2.82 to 2.9 i don't have that issue, but the entire add-on doesn't work anyway.

Environment:
Windows

[JanOtt]

Hi! I haven't been working on this addon for years now, so I can't really provide any help or support. Please try asking in the thread for this addon on Blenderartists (https://blenderartists.org/t/addon-shapekey-helpers/1131849/7).