This bug also occurs on iPhone 5s.
Issues Using Two-Finger Double Tap Gesture to Answer or End a Phone Call
Occasionally, when using the 2-finger double-tap (magic tap) gesture to answer a phone call, audio playback (another function of this gesture) will begin, rather than the call being answered.
Bug First Encountered
Device(s) bug has been encountered on
How often the bug occurs
I have an iPhone 5 and also notice this. A variant occurs on the iPad Mini Ii, wherein the magic tap does nothing to answer a call, but then all the controls to take a call go away. So either results in the ring ringing and no way to pick up, or the call being dismissed and the person has to call me back. Sorry if this variant could be classified as its own bug, but I think this is a general iOS problem.
Hello. I have not gotten a call since I updated to 8.2 yesterday. I hope they have fixed this bug.