I have the same problem with a MacBook Pro 2016. I tried everything, reinstalled the OS from scratch 3 times, the terminal delete command, and reset SMC and NVRAM. Once it worked for about a day and then it stopped working again. The problem started when I tried adding a fingerprint. Took it to the MacBook service center and they said they couldn't find the issue and that maybe it was the sensor and that the motherboard needed to be changed. That's way too expensive, so I am sticking with the MacBook like it is, everything else works fine, it's just that issue with not being able to use the touch id. And the message saying "Failed" or "fingerprint limit reached". I am sure it's a bug, because as I said it was working fine until I tried adding a fingerprint. And another time after resetting sMC and cram it worked for a day. Any suggestions will be greatly appreciated.