Someone else is still using this PC - Warning Message at reboot

Hi,
it is a few time (probably since the update to Windows 1903, the actual version that I'm using) that when trying to restart Windows, I receive the warning message "Someone else is still using this PC".
I noticed a strange thing along this: the "Processes" and "Users" tabs in the Task Manager are completely empty (sorry for the italian language, "Processi" means "Processes" and "Utenti" is "Users"):



I also noticed another strange thing: this is not happening anytime. For some time after Windows has started, the two tabs in task manager are fully populated and I don't receive any warning message if trying to reboot. I don't know for what reason this changes after some time.
I already tried everything suggested here:
Logout warning "Someone else is still using this pc"
From disabling the flag in the accounts settings (I've only one account) to creating the registry key.

Any ideas about this?

Thanks

Hi Caledon, thanks for the answer.

I've tried to run a sfc /scannow but it didn't found any integrity violation.

Thanks

Andrea

Thank you! Will try to do it