Overview blank going from 7.4 to 8.0 - simple thermostat issue

I have four lovelace dashboards defined…three are yaml, but my main dashboard (Overview) is UI controlled. In 7.4, the overview and the other three dashboards all worked. Once I installed 8.0, I just get a blank screen looking at Overview.

If I restore the 7.4 backup, the overview shows normally.

Did you clear the browser cache ?

yes…the other views show…just the overview that no longer shows. A clue: when I first (re)start HA, the overview very briefly shows and then is overwritten (or blanked out). There are no error messages. Without any log message, it’s hard to diagnose if it’s a hacs frontend addin or just what might be causing my problem. I’m hoping someone else has a similar problem and we can compare notes, so to speak.

I should have mentioned I am running HA under Bullseye…but I don’t believe that’s what’s causing the problem. Yes, I know that’s not officially supported yet, but Bullseye will be released this week.

Found the problem: HACS: Front End: Simple Thermostat

when I removed Simple Thermostat, overview works as expected. As soon as I add Simple Thermostat back, Overview goes blank.