I tried the Follow me feature on my Dji Spark. It worked fine at first. After a few minutes, it stops following me and hover about 3 meters above the ground. The drone did not register my gestures at this point. I cannot retrieve it either. I just have to wait until the battery is run out and the drone lands by itself. What went wrong actually?

Hi SharifJohn, Spark doesn't have the Follow Me function, so you mean the ActiveTrack, right? You are recommended to refer to the user manual and try it again:
https://dl.djicdn.com/downloads/ ... _Manual_v1.6_en.pdf
If there is any further issue, please feel free to let us know. Thanks.