Subtitles on Nvidia Shield stopped working

[boblinthewild]

There are two other reports of this problem:

https://forums.plex.tv/t/unable-to-play-mkv-videos-with-ass-subtitles-an-error-occurred-while-attempting-to-play-this-video/

https://forums.plex.tv/t/android-tv-version-8-24-0-breaks-ass-subtitle-and-truehd-transcoding/