Physical players do use the “forced” attribute on a subtitle stream.
That’s actually where this slightly confusing moniker comes from (there is nothing “forced” about it).
The difficulty is that a certain disc ripper software is not copying it into the ripped file.
So you always have to inspect the various subtitle streams and determine which one is the forced one and which is regular, or SDH, or commentary, or song lyrics etc.pp.
Put MediaInfo and Subtitle Edit into your toolbox. They can help with this task.
Also, the automatic stream selection in Plex stops working if you ever change the subtitle or audio selector manually on a video. The last manually selected stream is saved in the server database for your user. In order to delete this and revert to the automatic selection, you’ll need a complete Plex Dance of the item in question.
