I’ve noticed that a few shows I recently downloaded from my TiVo and synced onto my iPad Air 2 (iOS 11.4.1) are not playing audio and, when I check the settings, it shows no audio tracks. The audio is present when I play them using the TV app.
MediaInfo says it’s an AC-3 Dolby Digital track (16 bits, 6 channels). There is a short (less than a second) burst of the soundtrack and then it drops out.
I’ve never noticed it before but I transcode most of my downloaded videos and add an AAC stereo track if it is missing. The ones with a problem were not transcoded.
They play fine on my ATV4 and in iTunes.