I sympathise. Wish I had an answer but been looking for it for over two years. You aren't going to like my answer much, but problem started with an update to software and firmware while using a Phantom 3 Pro with a Samsung Tab 3 tablet. (clearly one that is listed in Dji's own data on compatible devices) I tried re-setting the tablet back to stock as it had previously worked. No help. To make it work, I bought an ipad. Nothing on it being used except the stuff it came with and the (now) Dji Go4 application. Worked for a year, then got another firmware/software upgrade the other day and started having similar issues to what you are seeing, but this time with a P4 phantom. Again, though, just installed a recent firmware and software update! One thing I think I am seeing? Dji is probably being asked by officials to add safety features to their software that just seem to totally mess up the needed functions! Dji GO 4 app has become so overwhelmed by added (and mostly insignificant) abilities that it stresses the tablet's ability to run properly. Hope they get back to basics some day.
Gosh, for a first post, I sure got over enthused. Sorry bout that. Been watching the group and have learned quite a bit. Just never took the time to join in. OH! and even now, with the Tab 3 used, I can fly the copter. Just have no video. Records to the mem chip fine. Quality of recording, good. Can use take off or Go home commands on the tablet. All seems to work except video.