While working with the terrain editor, I have been able to reproduce this with regularity. I'll try to get it on film. What I've seen happen is on a diagonal runway, like NE, if the edge (vertex?) of the terrain square slopes down even a little on each side, the drones (at least the very end one) tends to flip-flop nose-to-tail like a crack addict. When you start your takeoff roll, the drone(s) may be pointing the opposite direction and start going the wrong way and eventually warp and disappear.
My solution was to make sure the airfield terrain is truely flat for one square all the way around the perimeter. Like I said, I'll try to make a film tonight when I get home.