I had this once a week or so ago and then again twice tonight within about an hour. Phone behaves normally and then suddenly refuses to recognise TouchID.
Before anyone says I'm doing something wrong, my finger was dry and clean in all cases and, in any case, its not even registering the finger (or thumb) to say 'try again", its just saying slide to unlock (which doesn't normally appear when Touch ID is enabled). Pressing the power/wake button has no impact either.
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I've had my 5S since mid/early october whenever it came out. Been totally happy with it so far but lately (in the past 2 days) TouchID suddenly stops responding. As in when I press the home/lock button and rest my finger on the sensor, it doesn't do anything, and eventually after a few seconds displays "slide to unlock". It's like the capacitive ring isn't even recognizing that my finger is there because there is no indication that it is scanning/trying to scan my finger.
Restarting the phone fixes this but I was wondering if anyone's had a similar problem? I'm hoping it'll go away soon.
Given that the phone doesn't normally display "slide to unlock" when TouchID is enabled, I think the phone is not even registering that TouchID is active when this happens. I'm hoping this is a software issue that can easily be fixed.
EDIT - ah no, I see now that "slide to unlock" does appear after a second or two if TouchID isn't successful straight away.