I think I might have found the culprit
On the Mac under preferences Sync | DEVONthinkPro1 the LOCAL databases seemed to be hung on syncing the “Inbox”, just kept spinning from this morning. So I trashed everything in that folder I didn’t need. Shutdown, restarted, looked at Sync again.
The missing files populated in both ways.
Thank you for checking in. Yes it appears that the issue is resolved.
It seems the Mac wasn’t completing the syncing process. The moment I purged the database that was not finishing I could see the syncing on the Mac finish the rest of the syncing in a matter of seconds.
The iOS devices were syncing with each other (iPad/iPhone) almost instantaneously, it was the Mac that was causing my issue by holding up mid sync and not allowing the next database to sync.