I had the same issue. The only solution I've found was to stop synchronisation from the most current device (just to be sure) and have it delete all data stored by Enpass from my onedrive account (It should ask wether you want to do that.). After that, I've setup sync again and suddenly all my devices were able to sync.
Note: I've backed up (export as .json) my local passwords as a precaution before doing the above steps. The .json file is not encrypted, store it in a secure location or delete it after fixing the sync issue.