The FP scanner on Xperia 1 is known to be finicky, and can have FP recognition issue. Sony has tuned the scanner several times along the monthly SW updates, but the issue is never fully resolved. People worked around the issue by adding several entries for the same finger, and usually this improved the recognition rate to an acceptable level.
https://www.amazon.com/Sony-Unlocked-Smartphone-CinemaWide-Display/dp/B07PHQ7FBP