Hello JB's Forum Name,
Welcome to Apple Support Communities!
We want to help ensure the files are syncing to iCloud Drive as expected. Are you using the files with another file management service? See here to ensure your settings are correct:
"On your Mac
- Go to Apple menu > System Settings or Apple menu > System Preferences, then click Apple ID.
- Select iCloud.
- Sign in with your Apple ID, if you need to.
- Turn on iCloud Drive.
To add the files from your Mac Desktop and your Documents folder to iCloud Drive, turn on Desktop and Documents.
- You can then find your Desktop and Documents folder in the iCloud section of the Finder sidebar.
- If you add a second Mac Desktop, you can find the files in your Desktop and Documents folders in iCloud Drive, in a folder with the same name as your second Mac. The files from your second Mac won't automatically merge with the files on your first Mac.
If you already use a feature from another cloud provider that syncs or manages your Desktop and Documents folders, you need to turn it off to use Desktop and Documents. Desktop and Documents requires macOS Sierra or later."
This Apple Support page has the full details: Set up iCloud Drive - Apple Support
Since it sounds like you've already take these steps, does a normal restart of the Mac have any impact? Does testing while connected to another network help isolate the issue?
We hope this helps to get the files to sync as expected again.
Cheers!