Windows Server 2019 DC/Std odd permission issues with UI options

Having this problem with our domain-joined Windows 10 PCs.  "Restart now" in Windows Updates gives error "We're having trouble restarting to finish the install. Try again in a little while. If you keep seeing this, try searching the web or contacting support for help. This error code might help: (0x80070005)"  

Unfortunately the suggested fix here of adding the user explicitly to "Local Policy -> User Rights Assignment -> Shut down the system" did not work for us.  Rebooting from Start is a workaround, but we've found if users don't manually restart in a timely manner after updates, the Updates nag screen comes up the next day, takes over the screen, and apparently immediately hangs so the user cannot continue.  Likely this is also related to the problem. A mystery!