@oranges in the recent update 6.9.0 they have mentioned in release notes that windows hello auth may required second times. Can you please confirm are you facing this problem each time when you unlock the app using windows hello??
:https://www.enpass.io/release-notes/windows-10-desktop/
Strengthened the security of your vaults by optimizing the key generation process. The encryption key derived from your master password, which is used to secure your data, will now undergo 320K rounds of PBKDF2-HMAC-SHA512 iterations, a substantial increase from the previous 100K rounds. All existing vaults (excluding backups) will be upgraded. (Note: May require a second authorization for using biometrics)