I advise you to go to Settings > Touch ID & Passcode and add your fingerprints again there.
As for the screen blacking out during phone calls, this has been around for many many years now and it's normal behavior of the phone. Nothing to worry about.
However, if you feel something went wrong during the update process, you can restore your iPhone and see if you still have any issues.
If you have any further questions, please join our forum here
https://passport.mobilenations.com/register-im. We're happy to help.