I had suspected AppCenter problems, but in the meantime I think that this is a symptom of a more severe problem. When I try to use FlatSeal or Logs similar problems occur, in FlatSeal I cannot change the current selected app in the left navigation (most of the time) by a single click on the app, double click works sometimes, although only in rare exceptional cases, but most of the times nothing happens. Same in Logs: I can select in the last boots drop down, but when I click in the left navigation (Important, All, Applications, System, Security, Hardware) nothing happens (also most of the time, in rare cases a selection happens). I guess this is a problem also in other applications, but for these three (AppCenter, FlatSeal, Logs) I was able to reproduce the behaviour (except that I have no clue, why and when the selection works). I suspect that it is some problems in accessing a message bus due to some errors I saw in the output of journalctl.
eos-diagnostic-230720_115306_UTC 0200.txt (1.3 MB)
What can I do further to help in tracking down the problem.
Strange misbehavior of selection in gnome applications
The problem may be caused by an interaction with “Another Windows Session Manager” and/or the “Gnome Extension Manager”. I installed both due to my desire to have something similar to hibernate and the hints I got from @wove and @wjt but I encountered problems with it.
Apparently the problems have been resolved in the same mysterious way as they started. Currently everything is working without any problems. I am still curious, what could have caused the misbehaviour. I had a deficient Gnome extension installed, which was disabled. This might have been the reason, but I am not sure.
The problems returned. I still have no idea why and what I could do for testing.
I include a new eos-diagnostic-230803_123236_UTC 0200.txt (1.6 MB)
in the meantime, I found out that this problems seem to be tight to my account. I created a new user (with admin rights) and when I log in as that new user, selecting in the left pane in logs, app center and flatseal works as expected.
But I have no idea how I could track down the problems in my profile.