Hi John,
Same thing happened to me, however I was flying in very good conditions roughly 60m high and 250m away can still see the drone when the RC disconnected, my screen went blank on my phone and the controller kept trying to reconnect.
I rang DJI Australia and raised a case with my main issue being that the setting when RC disconnection happens the drone should return home this failed and thus drone is lost now.
DJI responded with a 30% credit, I did not accept this and asked them to review my case again as there is clearly a fault as the drone did not RTH upon RC Disconnection. Send them an email raise a case and they will email you a doc to fill out.
Hope this helps.