Rare, but try: Go to Settings > Security > Fingerprint > remove all fingerprints > reboot > re-add.
Upgrading from Android 5.0 (Lollipop) to ASUS ZenFone Selfie Z00UD firmware 6.0.1 brings tangible benefits:
For the Z00UD, the Android 6.0 update was not merely a cosmetic change; it fundamentally improved the hardware utilization.