I tried to use follow mode yesterday, with an iPhone 6. It started out perfectly- Phantom was following me 120 feet up and 100 feet behind me. As I walked through some light tree cover, the P3 stopped following. It hovered in place, but kept adjusting its heading to face directly toward me. After I got maybe 500 feet ahead of it, I noticed it was far behind me. I waited, and suddenly it raced toward me to catch up and resume its former position in relation to me. Again, though- it didn't follow, just hovered in place, but it kept turning slightly to face directly toward me, which makes me think it knew where I was. I finally had to take it out of F mode and fly it manually to catch up. Did this twice. It never did follow me again. I would think maybe the light tree cover was giving me a weak GPS signal on the phone, except that it kept changing heading while hovering to face directly toward me. Also, I've walked the same route with my phone and never noticed any loss of GPS signal. Any thoughts would be appreciated.