Same issue... Tried backing up the database in settings and restoring it but no luck. Able to open notes in the app and able to add new ones but freezes when I try to retrieve any passwords. My son has the same issue as well so it may be something with the recent upgrade. No response from the developer (its been a week).
I was able to open the .sqlite file and see the usernames, comments, and notes but the passwords are encrypted as they should be.
Everyone always tells you to use a password app like its a best practice. It is impossible to determine which ones will continue to be supported through IOS upgrades. This has been more of an "android" experience for me as I've often had issues like this in the Play store. Never on IOS though.. until now.