I downloaded a Mavic Video (< 1 GB, 4k, MOV and MP4) to my iPad Air (ios 10.3, 40 GB free Memory). Video appears in Photos - but cannot be played back. I see just the first frame, if I touch the > button, I only get the "loading" circle thing... Also import into iMovie does not work (it's not even offered as a source)... Any ideas?