iCloud Drive on Mac never fully syncs
Site insists upon a new thread; 2 methods that have succeeded is to 1) go to the Activities Monitor and use the stop-sign icon to kill the 'bird' process (the process will re-start by itself) or 2) from your machine open Safari and log onto iCloud.com, download any file of yours from iCloud.com through Safari to your local machine's downloads folder, which afterwards seems to get syncing to kick back in.
Turning off and back on iCloud from Sys Preferences sometimes succeeds, oftentimes doesn't
Hope these workarounds are useful.
[Edited by Moderator]
MacBook Pro 15″, macOS 12.7