"Did you try the RTL while on the ground at the boot up point? I did that and the throttle didn't work. Once I tested it in flight the RTL worked perfectly with throttle control. The APM must know that it is not in flight and already at launch point…"
"Did you try this on the ground? It did the same for me but works fine in the air. I believe it knows that it is still at the launch point and will not wind up the motor. I did my test using RTL and motor didn't turn but when tested while flying RTL…"