Sorry for your loss...
I've had "Return Home" work fine several times, but I've never flown at your distance with this flight. But I have noticed on several occasions while flying "Ground Station" flights using DJI's app, that when the P2V+ had to make a turn at a waypoint approaching 180 degrees it would initiate the yaw, make it partway, then yaw back toward the prior direction, then resume and complete the required yaw to the next waypoint. My heart would drop as I observed this happening. In each case where this happened I had at least 9 GPS satellites, the rest of the flight was normal, but at that turn the P2V+ seem "confused." Was it not getting the correct inputs from the on-board systems?
I guess it is possible the Phantom could be so "confused" for some unknown reason it couldn't complete the turn and get to the next waypoint, or return home.
I've had "Return Home" work fine several times, but I've never flown at your distance with this flight. But I have noticed on several occasions while flying "Ground Station" flights using DJI's app, that when the P2V+ had to make a turn at a waypoint approaching 180 degrees it would initiate the yaw, make it partway, then yaw back toward the prior direction, then resume and complete the required yaw to the next waypoint. My heart would drop as I observed this happening. In each case where this happened I had at least 9 GPS satellites, the rest of the flight was normal, but at that turn the P2V+ seem "confused." Was it not getting the correct inputs from the on-board systems?
I guess it is possible the Phantom could be so "confused" for some unknown reason it couldn't complete the turn and get to the next waypoint, or return home.