I hadn't realised that the issue is only with Open-Shell Start Menu so it should not affect those who do not have Open-Shell installed. I don't have Open-Shell. I have StartAllBack installed so I updated v154.0 and all is okay.
Sorry for the misunderstanding.
Could it be heat related due to being running while plugged in and the lid being closed? Heat build up can cause shutdown so maybe hibernate as well? Just guessing here.
Q1 - Which of your two systems is this happening on?
Q2 - Had you installed anything (software or hardware) just before this started happening or did it just start on its own?
Q3 - Are you able to update your two OS's to the latest version and build? 25H2 Build 26200.9168.
If you only use your Office for creating local documents on your own machine then keep running Office 2021 even after support ends. That's what I am going to do.
It only becomes important to upgrade to a supported product if you are file sharing.
Try a repair install but be patient. It took 1 3/4 hours on my GMKtec device but it worked: -
https://www.elevenforum.com/t/repair-install-windows-11-with-an-in-place-upgrade.418/
I agree with @FreeBooter . Just be aware you will need to be patient. On my GMKtec device it took 1 3/4 hours via the Settings > System > Recovery > Fix Problems using Windows Update method.
Good luck.
Do you Bitdefender installed?
I have Bitdefender Total Security installed and when that updates itself it is temporarily disabled and I get a 'Turn on virus protection' popup in the system tray area but it disappears when Bitdefender restarts itself after updating.