Issue with groups - applications not working properly


after installing updates, I can no longer log into wifi networks (“No valid session for uid 1000”), audio devices aren’t shown and the user manager doesn’t do anything upon adding a new user.
I assume this is an issue with polkit, since it worked without adding myself to all those groups like audio, etc. before. Any leads? Can I somehow reset all users to their default settings, reconfigure polkit and so on to make it
work again?

(polkit is on version 0.113 by the way)

Any help is very much appreciated. And if there isn’t a fix for this, what groups do I really need to run the system without any problems?

Thanks in advance,

May be this problem