Does the media have Dolby Digital Plus (EAC3) audio and is the audio transcoding?
If so, it is a known problem. Workaround is to use Play Version or not select subtitles until after playback starts.
See Multiple Version and Audio Transcode Issue on Android
Problem description: Multiple Version and Audio Transcode Issue on Android - #13 by FordGuy61
Verification that subtitles are involved: Multiple Version and Audio Transcode Issue on Android - #60 by FordGuy61
