Most of my media is converted to MP4 with mov_text subtitles from when I used plex with the old player - though I continue doing so due to ‘Subler’ converting graphic based subs to text based, which I prefer.
Only issue is I have noticed when I use Channels on an Android TV, I cannot enable embedded mov_text subs.
Is there the potential for this to be added?
Does it show up on the list? What happens when you enable it?
Need diagnostics submitted from the app after you try to enable
Seems to be playing fine on my Sony TV. 
I’m sure at a family holiday house in an Nvidia shield I could not get them to work. Just had forgotten to report until now.
I’m going up there this weekend, will test it out again and report back.
Okay maybe it's a remote transcoding thing
Possibly, just got up here now and gave it a test.
Tested Toy Story 2 but it had an SRT that was labelled very weirdly. Track 1(then a whole bunch of gibberish)
Then went to a Severance episode I was watching that has only mov_text. Streaming over ‘internet streaming’ at 4mbps. No subtitles were listed to enable.
Edit: submitted diagnostics after doing all this.
Edit 2: setting Internet quality to original makes the mov_text subtitles appear.
Tested on my Google pixel tablet before I left and when set to ‘stream’ and playing over the home network I would get mov_text subtitles playing, even when transcoding.
But now while I’m away from home, streaming via ‘Internet quality’ I no longer get mov_text subtitles - unless the bitrate is set to original.
So you’re original guess seems to be right @tmm1 that while transcoding away from home that the mov_text subs seem to get lost for android/android Tv.
Photo of tablet without subs when set to 1mbps and one with subs available on original.
