I've been having this issue using my Samsung S6. I've found it occurs on the long range MPCC. I have a theory that when it get's at the edge of the range, you might set a point on the controller but the bird being at the end of range misses that point. then when you get back and push B, the program compares waypoints on bird and on controller and finds it's missing one, so it bombs out. I went back to the path I was having trouble with and flew it as I wanted, but only Pushed A where I could tell the signal was decent as displayed on app. worked fine.
If I'm right, there's likely something that can be done if the bird doesn't get the waypoint to avoid the wasted effort, at the minimum, I wish the controller wouldn't beep like everything is fine.