I bet my last answer is pretty close to accurate.
>>>>I am having the same problem, Also I used to use a app that cleans computer then shut down, but will not shut down. now since windows update.
You start running CCeaner or use a registry cleaner, 2 virus programs, install free software loaded with malware and many other things and this is what causes this 98% of the time.
Connected devices to PC could be causing it.
Print queue with items left in it causes this.
Corrupt software installation of just 1 program causes this.
Have you looked in start up in task manager and disabled everything and tried to log off, log on and log off again ???? Including defender
Have you looked in your programs and features at all the programs installed on your pc for unknown programs that 80% of pc users install by accident or are malware with free software.
And especially a corrupt or hung network or configuration can cause this.
modem reset and all pc restarts can fix this.
You have to analyze it and diagnose and process of elimination.
Then, have you looked in details in task manager for a program that might be running and low CPU% usage that is suspicious.
There is 50 reasons why this could be happening.
Even a windows service, very possible is not shutting down on log off or restart.