I had the same problem with my Phantom 4 Pro, and apparently if you are using a IOS device, and using safe mode, so the drone stops every time it has to take a picture. This means that everytime the drone is supposed to stop, capture sees that as a waypoint, and for now it’s only capable of having 99 waypoints. So this means it automatically returns home after the last waypoint.
Try using fast mode and slower speed, it should solve problem.