VLC not showing subs.

I have a odd issue that has been cropping up lately and with .mkv subtitle built in files. Some files it will show the subs, others it wont despite selecting in the menu show subs, and selecting the track. VLC 3.0.12-alien is the version I am using. I did a full rebuild from source to make sure something wasnt awry.

Test case I take the same mkv file and play it in mplayer and xine and both show subs but not vlc. I have tested tons of mkv files from various sources and certain ones just do not want to render.

Is there some bug with vlc, is there a newer standard for subtitles that isnt working right? There is no seperate sub files.