Developer option
- Settings - My Device - All Specs
- Tap 5 times in Miui version
after that you will get developer option in additional settings.
Go to Settings - Additional settings - Developer options
- Dont keep activities (disable this)
You have more fix's if u can try -...
Try Reboot your device and remove all your current Fingerprints, clean the Fingerprint sensor area and your fngers, and then re-add Fingerprints.
Wipe Dalvik and cache in recovery mode and try again
Hope it works.
- I flashed with CN Dev 8.1 - http://www.miui.com/download-332.html with clean all
- Inside Twrp Wipe everything except (System)
After that i installed EU