Nooo. I did indeed have many, many files downloaded.Actually, >40Gb of files (or more than 34,000 files) are completely synced between the cloud and the local drive.

slicendice. Apparently I wasn't clear in my original post. When I right click on the OneDrive folder in File Explorer and on any subordinate folders, the option "Free Up Space" is grayed, disabled,...

"Free up space" is grayed for all folders, including the base OneDrive folder. Only individual files can be made Available Online.

Thanks. I had run sfc /scannow before I did the Registry thing, and it found no integrity violations. I'm not sure if sfc actually checks Credentials Manager.

Actually, I had already tried turning the option on and off as described in Option 1 in the link you provided, at least three times. That didn't work, so I tried it a couple of more times when I got...

I have a Windows 10 Pro machine that is in a secure location. Using the User Accounts settings (netplwiz) , I unchecked the option, "Users must enter a user name and password to use this computer."...