A track or subtitle is missing

Track names are missing, but another player shows them

The video is probably an MP4. Track names there are kept in a QuickTime udta/name box, which some players read and TinePlayer does not, so the tracks often appear with no name and no language. MP4 also carries none of the flags Matroska uses to mark a track as description, forced, or SDH.

Converting (remuxing) the video to MKV without re-encoding will copy the tracks to a container that TinePlayer can correctly read.

A described track is not chosen automatically

Check that Prefer Audio Description is on for that output. If it is, the track is not flagged as a description or its name is not recognized. See Audio description for how audio description tracks are matched.

A subtitle track in the video is not listed

Some DVD and Blu-ray subtitles are stored as images rather than text, and are currently not supported by TinePlayer.

A subtitle or audio file beside the video is not listed

Check the name. It has to be the video's name, a dot, then the language or kind, so a name that only begins the same way does not match. See External subtitle files and External audio files. The exception is a folder holding one video and nothing else, where anything in it is listed whatever it is called.

Files are only looked for beside a video opened from a disk or a share, not one opened by URL or cast from a library. You can still choose one with Browse... at the end of the list.