I was homing and a pencil stopped it from homing. Of course, it alarmed. The only way I know to clear them is to restart. When the system came back up I did the double tap to Home it. It stopped just short of the home position and started flashing Homing Please Wait. I waited for a few minutes but it continued. Then wait for hour doing others things in the shop. But whenever I checked it no change.
Starting thinking, what if I just move x -bar and z-bar a bit while it is powered off. Turned it back on and sure enough homed as usual.
Glad we could help 
@woodskills
Whenever I have an alarm, I engage and disengage the estop button and home the machine. This removes the alarm for me.
You might have to manually turn the screw to move the sensor away from the trigger first.
Pat