I had that error for the first time today (Windows 10, Enpass 6.4.3, OneDrive).
Out of nowhere sync failed.
Here is what I did:
made a lokal Backup on my WIndows 10 Computer
looked directly in OneDrive: There where 2 Folders: "Enpass" and "Enpass 1"
made a backup of both in zip Files
disconnect sync with doption to delete sync file on one drive (to look which of the folders would be erased: "Enpass 1")
deleted remaining folder "Enpass" directly in OneDrive
created new sync connection with one drive
Everything was immediately back to normal:
there was no need to do anything on the other devices, no reset, no disconnection, nothing
all other devices could immediately sync, as if nothing ever hapened
Enpass simply corrupts the sync file on the server, for whatever reason