S2 9.7 and 5.1.1 update = flakey fingerprints

Out of the box my n s2 9.7 came with 5.0.2 and finger print sensor worked rock solid. Recognized first time, every time. After 5.1.1 update it rarely recognizes my prints and I usually need to enter the password. Factory reset and alternate fingers don't work any better. Always completly stock. I returned first unit but second one has same issue.

Anyone else experience / fix?