Problem recording fingerprints. Keeps going back to previous screen before it is done

By design, when registering a TouchID fingerprint, you must place and lift your finger many times - each placement scanning the ridge-detail of the fingerprint. TouchID is always learning; each scan further refines the recorded detail.

I've never counted the number of placements required, but you anticipate ten or more placements to properly register each fingerprint that you register with TouchID.

Set up Touch ID on iPad - Apple Support

Contact the developer of the app you’re using for fingerprint recording. It’s the developer’s responsibility to support their products they make available on the Apple App Store.