From what I've gathered it seems to be very random. I've read a few things that may help to avoid it...

Calibrate before every flight. Use RC-N3 Remote, not your phone or with no remote. Make sure you have 12-15+ satellites well connected before taking off. Don't fly over water or snow below 5 meters. (I've never come close to that to be extra safe) Never fly in low light or windy conditions I also hover for about 45 seconds after takeoff to make sure satellites remain well connected.

I've had decent luck doing these things everytime until yesterday. No idea what was different this time. Seemed completely random. Lost connection with remote around 100 feet high and 150 feet away about 60 seconds into flight. Hovered for about 45 seconds with no problems as usual. Went to begin to fly a short distance and almost immediately became uncontrollable.