The password she thought was the Master does not work on the new phone.
Recovery options do not work; she never used it on a browser, and never had browser extensions installed.
The only computer she might have used to log in with a browser failed like a year ago.
There are no recovery "hints" saved when trying the "hint" it is blank.
But it's STILL WORKING on the personal phone!
So, how to recover a PW using the working phone? Biometric recovery is ENABLED and face recognition is ON and works (iOS). It looks like to recover using biometrics, you would have to log out, then select "trouble logging in". However, she wont' log out as she thinks she'll lose all passwords. I also see there is no way to export passwords from the iOS app. How is the best guaranteed way to recover and reset a Master if you have a known working phone with face recognition and biometric recovery set up?
When trying to log in on the new device with the master password (NOT trying to reset the password, just logging in) what error message do you see? If you see an error that says "Try again or look for an email from LastPass," please check your email (including Junk/Spam/All Mail folders) as you may need to verify this login via an email message.