I just found the thread after hitting the same issue. Was quite surprised, as macOS without iCloud is very limited... many reasons as given above.

I am seeing the same - at least daily if not more often.

Any tips on this? I'd really like to be able to at least get a pointer to what could be wrong. Here's an example of the begining of the file: {"timestamp":"2021-11-29 07:36:36.00 +0000","bug_type":"210","os_version":"macOS 12.1 (21C5039b)","incident_id":"3E1E5703-01AC-4D50-86C8-8B1C811874B0"} {"macOSProcessedStackshotData":"RGF0ZS9UaW1lOiAgICAgICAgMjAyMS0xMS0yOSAwNzozNDo1NC42ODcgKzAwMDAKT1MgVmVyc2lvbjogICAgICAgTWFjIE9TIFggMTIuMSAoQnVpbGQgMjFDNTAzOWIpCkFyY2hpdGVjdHVyZTogICAgIHg4Nl82NApSZXBvcnQgVm

I've just tried STP 127 hoping this might be fixed - but now I can't see tab groups at all - indeed other design changes found in 126 appear to have gone

Unfortunately this makes them rather useless for me for now as my lovely curated groups all disappear on exit :-( I get it's good to get the idea out there for devs to test, so maybe the rest isn't ready yet, but a release note reference would have helped if so.

I've had the same here on a 2016 MBP. I mostly use an external screen. It's occasionally come back (once without rebooting), but mostly is missing. The settings look correct. Not a massive issue, but annoying