SUMMARY
With Neon unstable edition full updated, logging in to an updated user account, or a newly created user account, activities do not function properly: the desktop wallpaper and widgets change, but window filtering does not work - all windows are shown, regardless in which activities they were created and the window operation menu does not have the expected "Activities" sub menu to allow to set the correct activity for a window.

Also:
- Window rules that had activities set in them do not cause the windows to be filtered out from other activities and there is no way to set activity when editing/creating window rules.
- The task manager shows all windows even when its behavior is set to "Show only windows from current activity".
- The "Activities" view shows the correct activities and lets me switch between them, as well as the activity list widget in my panel also behaves as expected.

STEPS TO REPRODUCE
1. Have two or more activities enabled.
2. Start an application.
3. Switch to the other activity.

OBSERVED RESULT
The application started in step (2) is still visible on the screen.

EXPECTED RESULT
The application started in step (2) should not be visible on the screen as it is in the other activity.

SOFTWARE/OS VERSIONS
Operating System: KDE neon Unstable Edition
KDE Plasma Version: 5.90.90
KDE Frameworks Version: 5.246.0
Qt Version: 6.6.0
Kernel Version: 6.2.0-37-generic (64-bit)
Graphics Platform: offscreen
Processors: 20 × 12th Gen Intel® Core™ i7-12700H
Memory: 31.0 GiB of RAM
Graphics Processor: Mesa Intel® Graphics

ADDITIONAL INFORMATION
In the past I had this behavior when the `plasma-kactivitymanagerd.service` user service has failed and restarting it fixed the issue, but this is not the case - the service is running properly and looking at its logs (using `journalctl --user -u plasma-kactivitymanagerd.service`) does not show any warnings or errors.