[oldpoem]

So I got xyvsfilter to load and work (I can turn working subtitles on/off from the xysubfilter settings window), but I still find that really few embedded subtitles in mkv containers actually work.
I can see 4 different subs for a movie in the Kodi subs menu, as well as in the DirectVobSub context menu, but none of them work when selected.
With the Kodi standard DVDPlayer I can see only 2 subs in the Kodi menus for the same movie, but they both work.

Anyone know why this is? Both xysubfilter and xyvsfilter seem to have the same problem described above.

This is not normal. Is this happens only to specific files or most files. How did you encoded the file, which softwares did you use? What does MediaInfo tell you about the problem file? Then upload some samples of problem file for others to see. The file you mentioned might be wrongly created.

Need a lot more information. Also Kodi DVDPlayer actually a very reliable in playing subtitles. Also you can try other player to see if the file indeed has 4 subtitles selectable tracks or not.

Also try to remux the file with MKVToolnix to possibly correct wrongly created media file.