We currently facing on multiple clients with update issues from Windows 10 1803 to 1909 or from 1909 to 20H2. The Clients stuck in an update loop and after a restart the update is not installed.
We have found that the key PendingFileRenameOperations REG_MULTI_SZ \??\C:\WINDOWS\TEMP\Upd....tmp exists for these clients under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\.
After evaluating the key, we could see that the client tries to delete this tmp file after reboot.
This file belongs to Winzip. After this entry was deleted, the computer was restarted, "Restart pending" was deleted.
We have already opened a case for one week now.