Fire TV 4K doesn't show VOBSUB subtitles

Plex Players Streaming Devices
1

Server Version#: 1.28.0.5999
Player Version#: 9.6.2.34353

The saved subtitles in VOBSUB format inside of MKV files from my original DVDs are not shown when I stream my movies via a FireTV 4k stick.

Additionally, when I download SRT files, the settings for delay of the subtitles don’t seem to work, I can’t get the offset between picture and subtitles away.

2

It’s not just FireTV. Seems to be broken on Android in general. Also not working on my phone unless I change the subtitle burning option to “Always” so it gets transcoded on the server.