Garageband 'enable audio units' greyed out!

I noticed that on an old project my AU were organized neatly. There were categories per developer and two menu options for "AU Instruments" and "AU Generators".

In a newer project, with greyed out "enable audio units", there was only a menu "Audio Units" and the AU where all over the place in long lists and many were missing!

Then I opened a brand new project and that had the same problems as the newer problem. Although... I was able to uncheck "enable audio units" and check it again... and then the AU were organized again.

Anyone found this too?

Older project: "enable audio units" blue, not grey

newer project: "enable audio units" greyed out:

For me the 'enable audio units' option is still active.

Could it be, that you are having incompatible third-party plug-ins installed?

My folders /Library/Audio/Plug-Ins/Components  and ~/Library/Audio/Plug-Ins/Components are nearly empty, so there are no potentially problematic items.