Same issue here. Win 7. Cloned my failing system drive to new SSD system drive. Enpass no longer works. Installed "last stable older version" 5.6.10 of Enpass. What I have tried: (1) When I try restoring the vault from Google Drive, as soon as I enter the password, it crashes. (2) When I try restoring the vault from a backup file, when I enter the password, it says "Incorrect Password." (3) When I try "I am a new user" and enter a password (any password, not just the correct one), it says "Vault location cannot be found change to default location" with a button that says "Change to Default" and then sends me back to the start screen. (4) I wanted to try to create a new empty vault to which I can add items, but there is no way to do that without entering a password first.
Spouse runs Enpass on her Mac with no problems. I tried changing the old master password on her installation, then syncing to Google Drive, saving a backup and also exporting three different ways. The new master password is no good on my system either. I tried uninstalling Enpass on my system, including deleting every file that I could find that refers to Enpass, plus running Ccleaner to try to purge it from the registry, somehow hoping to get a clean install of Enpass, but nothing made any difference. There is nothing I know to do to get Enpass to run on my system.
UPDATE: Problem solved. Here's what happened. In my box I have one SSD system drive and two hard drives. I also have an external USB hard drive. Years ago I assigned drive letters W, X and Z to these drives. I turns out that, in the process of pulling out one drive and attaching my new SSD to be the clone target, Windows decided to change all my drive letter assignments (except C). I figured this out in the process of fixing other little issues that were coming up. Then I thought, could this be what is confusing Enpass? Once I reassigned my drives, I tried to sync with Google Drive. It didn't crash but it said incorrect password. Then I tried restoring from the backup, and that worked.