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
sync
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
My conclusion:
Enpass simply corrupts the sync file on the server, for whatever reason