My last working configuration was APM 2.6 with Xbee 2.4 GHz radios. This worked great in both Andropilot and Mission Planner. I swapped out the Xbee radios for 3DR 915 MHz radios. The new radios work fine in Mission Planner. I can read location, telemetry, everything I'd expect.
HOWEVER, the new 915 MHz ground radio using the same OTG cable on my Android get stuck "Looking for Vehicle". It moves from "Looking for radio" to "Looking for vehicle" when I plug the new radio into my Android USB port. All the lights are solid green and the radios look happy, but Andropilot can't find my quad.