Windows 11 iCloud Settings doesn't save enabled state for iCloud Drive
A few weeks ago, iCloudDrive stopped synching on my Windows 11 system. At the time, the checkbox in the iCloud Settings app was checked, and all the new files I added to my iCloudDrive showed "Waiting to Sync" status. I did some debugging, and tried ALL OF the following:
1) Reboot system
2) Disable iCloud Drive (uncheck checkbox) and re-enable iCloud Drive
3) Disable iCloud Drive, reboot, re-enable iCloud Drive
4) Sign out of iCloud, then sign back in, then attempt to re-enable iCloud Drive (which failed)
5) Sign out of iCloud, reboot, then sign back in, then attempt to re-enable iCloud Drive (which failed)
6) Uninstall iCloud, reboot, reinstall iCloud, attempt to enable iCloud Drive (which failed)
7) Uninstall iCloud, delete entire AppleInc.iCloud... folder under "C:\Program Files\WindowsApps" folder (which took a LOT of effort, including changing ownership and adding permissions!), reinstall iCloud, attempt to enable iCloud Drive (which failed)
After the sign out/sign in attempt (try #4), when I would open the iCloud Settings app and try to enable iCloud Drive (check the checkbox, click apply), the iCloud Settings app would simply uncheck the iCloud Drive checkbox. Repeating this sequence (check the checkbox, click apply) gave the same results. Repeating things like signing out, rebooting and signing back in, or uninstalling iCloud and reinstalling and signing in did not fix the problem.
Nothing I do will allow me to enable iCloud Drive.
I've tried creating an empty iCloudDrive folder in a different location and using the Options button for iCloud Drive in the iCloud Settings App to point to the new location, and that did not change the behavior. Rebooting doesn't change the behavior. Signing out and signing back in doesn't change the behavior.
What is happening, and why can't I enable iCloud Drive on this PC?
It's running AVG Internet Security. I have not tried disabling that, because I don't like to leave my workstation vulnerable.
Windows, Windows 10