Quick PSA, I also had inexplicable fingerprint reader issues and found this topic. After ruling out a number of the usual suspect with the help of Framework’s fantastic support team, here is what was the issue for me, I’m just pasting my last mail to support …
Ok … wow … I fixed it. This must be a Windows bug:
So poking around in Event Viewer I stumbled across the extremely helpful folder “Application and Service Logs / Microsoft / Windows / Biometrics” where a number of “Verbose” events were listed. A few of them read
“The Windows Biometric Service cannot complete a request because biometric operations are disabled by current system policy.”
For a moment I felt really stupid because I thought I verified those options.
I then opened Policy Editor and went to “Computer Configuration / Administrative Templates / Windows Components / Biometrics / Allow the use of biometrics”, and the option was “Not configured”. The help text also said “If you enable or do not configure this policy setting, the Windows Biometric Service is available, and users can run applications that use biometrics on Windows.”
I still decided to force-“Enable” it, just to see what happens, re-opened Settings and, lo and behold, the fingerprint sensor was available again!
Lastly, just to test, I set the option back to “Not configured” and it still works.
tl;dr - “Allow the use of biometrics” was disabled despite the policy editor saying it wasn’t. Cycling it from “Not Configured → Enabled → Not Configured” fixed my problem. Also, event log for “Application and Service Logs / Microsoft / Windows / Biometrics” was great for debugging.