I’m also facing the same problem: Enpass requires the “password of data” and it does not accept the master password of the vault though the master password was not changed!
I tried disconnecting from Dropbox account, deleting the remaining vault file in Dropbox, reconnecting to Dropbox account, and then syncing again.
This worked well at that time. However, after several days, Enpass returned to showing the error.
Does anyone know the current situation to solve the problem?