Galaxy S6 Edge :: Why Does Phone Call Screen Disappear

The past few weeks whenever I make a call the call screen disappears. The bar at the top of the screen is green and my call is still active, but dragging down the screen shows no menu to hang up, mute, or speaker like it did in the past. Also I hit the recent programs button and there's no window for my call. I hit the phone button and there's nothing. The call will still show up in the log once we hang up. I literally cannot hang up without shutting off my phone. I can't mute my microphone or toggle speakerphone.