I just discovered that it had nothing to do with a
third-party device. Aside from the password problems just posted, I can't
access the screen after it goes to sleep when *any* device is plugged in. I
have an iPod Touch plugged in with an *Apple proprietary* USB-C to lightning
cable, and Touch ID refuses to work. Furthermore, the iPod Touch shows a
message saying "This accessory is not supported by this device" -
though it does appear to be charging all the same. I got exactly the same
message when I plugged in an iPad Mini (same cable), only this time it refused
to charge, IT'S ALL APPLE GEAR. What is going on here??