There is known issue that there will be longer logoff time if user immediately logoff after logged in if using Persona + Win10 (approx. 4-5 minutes).
When the issue occurs, please open the problematic VM using vCenter client and see what screen you see (print the screen).
If it's stuck at "Logging off" screen or other screen, then suspend your VM and you'll find *.vmss and *.vmem (depending vSphere you use) and submit to your support channel for further investigation.
Don't forget to collect agent log bundle after you restart the VM.
