Quick maxscripts commands to check if you need to clean your scene files/install:
These should both return false.
If they return true you should read the following AKN articles which include detailed information including how to cleanup your scenes and installs in case they are affected:
- Potential issues with third-party MAXScript (CRP): switching to different viewport/scene lights disappear or seem deleted (CRP)
- Scene file crashes, corrupts scene data, gives Script Controller error or no longer uses the Undo function (ALC)