I had the drone in follow mode behind a boat. A couple of times it could not keep up. No problem, stopped the boat fly the drone back and started again. Once we got the speed right, the drone was tracking as it should, then I got an aircraft warning. After that warning popped up, the drone stopped following and would could not fly it back to me. (no forward flight). I could move side to side, up and down. We had to move the boat under the drone to recover it. Does anyone know why it would have lost the ability to fly forward?? I was in sport mode the whole time. (This happened two or three times)