GCS error my drone come back in rtl

hello guys, i have a problem with my drone please help me, so my drone has a 50 km range, i made an mission in MP the distance is 15 km go and 15 return all good before 5 km after 5 km the drone start an failsafe and she come back to home in RTL.

Nothing to comment on without a link to a flight log.
And it probably doesn’t belong in a Mission Planner thread, I suppose it’s a Plane.