Hi,
This is an old thread, so pardon me if you’ve tried these things recently…
1. 6.7.2 is not the latest version of Enpass for Mac. Try upgrading to 6.7.4.
2. Remove iCloud syncing from your vault, remove the copy in iCloud if needed. Then set up syncing to iCloud again.
3. When asked to authenticate, let Safari launch. You will be asked via a special drop-down sheet if you want to log in with the currently active iCloud account. Make sure you don’t log in that way. Refusing will present the standard login screen for your iCloud account. Make sure you check the box to remember this login and then log into the appropriate iCloud account.
4. Once authenticated and passed back to Enpass, you should remain logged in unless your iCloud password is changed or you invalidate logged in sessions or you have some process that cleans up files related to Enpass in the background or you are logged into a guest account.