Just my two cents worth that is NOT based on knowledge of these systems, but from one experience.
Not realizing just how much power is used to run DJI Go on my mobile device I fired up a flight in very bright sunlight. I didn't rely on the screen much as the AC was close to me and I really couldn't read the screen anyway (before I made a shade box). Unbeknowned to me, my mobile went dead, capuut! I think I heard the voice on the DJI Go app say something about one second before the screen went blank (stupid me, I had the volume set too low). Once the device was no help I was about 15' up and about 100' away. I could not control the AC the way I thought it should. Stick inputs were working (AC would react) but felt like I had no control, and I crashed into a tree. No damage, thanks God.
My point here is that I believe I had trouble simply because I did not know the attitude of my AC. My stick inputs were probably working fine but **I** wasn't! I didn't have visual orientation of the AC. I could clearly see it, but it's all white and in the bright sunlight the LEDs were no help. I have been flying R/C aircraft since the beginning of dirt and had this same problem a few times with sailplanes that I let get too high and couldn't tell what I was doing. Always worked out though, thanks to their shape. Once those birds fall low enough, you can see what they're doing. Not so with a drone.
Just a thought.