Every time someone calls, I tap the answer button. Except it does nothing. No other button works either. I'm forced to wait the 30 seconds. Any fix (WP8.1DP, now W10)
Sounds like something software wise, try a soft reset (power button and volume down until you feel a vibrate). Though, if that doesn't work, you'll have to revert back to WP8.1 via the Windows Phone Recovery Tool.