Hi there.
Same problem for me. Starting this week. Didn't changed master password in any of them.
I'm using in three different devices.
OS: Windows 10 Pro 2004, build 19041.450,
Enpass: Last Enpass from Microsoft Store (can't find the version).
OS: Ubuntu 20.04
Enpass: 6.5.0.707
OS: IPadOS 13.6.1
Enpass: 6.5.0 (473)