OneDrive was going bonkers Sync-ing, or trying to Sync with Documents folder, and using up all of the c:drive memory. (About 46,000+ files.)
I finally selected a OneDrive directory and pressed "Free Up Space" in File Explorer, (Warning, this actions occurs in the folders subdirectories also.), to stop the sync-ing.
(So some files may be only in the cloud, at some time or other.(?)) ( I managed to un-sync one directory, and then un-synced all, or nearly all of document folders, using ignorance.:-)
(OneDrive via Office 365, 157.9 GB used of 1TB)

A simple help link:
https://answers.microsoft.com/en-us/msoffice/forum/all/onedrive-using-up-all-my-free-space-on-c-drive/e3c216f0-ee65-4e12-9d84-8e34d73bef49

Updated powertoys to v0.76.2, to restore preview of .js, (.htm as text, not as a run), and many other extensions (150+?). (Some file size limitations.)

.3dm file preview was (partly?), and is NOW working fine, for .3dm files saved "recently" (In last few months).
An older .3dm, without the preview "thumbnail", can be doubled clicked on (opened in MoI5Dec1beta), hit MoI save Floppy Disk icon, for thumbnail creation to that file in current directory. Quick and easy.
The load time for MoI for some large .3dm is fairly short, a couple of seconds, or very fast for smaller .3dm files.

I assume that the preview is from the MoI thumbnail creator.(?) Not Rhino8.1?)

Quite large .3dm's can get a thumbnail which previews.

There can be some brief time delays when previewing OneDrive files.

- Brian

It is very hard for me, these days, to know what is going on. Maybe blame setup of 3rd computer (baby Dell), due to selecting Link photos, phone?, other computers via internet???
Or maybe blame MS???:-)