MP configured to show subtitles that have the forced flag.
MP display some sort of "auto" subtitle entry selected - but no subtitle is displayed. This 'auto' stream is created from LAV Splitter (and will display only sub with Forced flagged frame). But we can have other forced subtitle track and MP didn't pickup this one.
We have to select the "forced" one manually.

h4. Steps to Reproduce
Select MPC-HC Engine for subtitle and set 'Subtitles will only display forced subtitles'
Open a MKV with forced track that match your MP language preference.
Start to play the MKV
'Auto' Stream is selected and not the one set with your language perf.

h4. Additional Information
Rework a little MPC-HC Engine to send user preference language.
MPC-HC Engine will select the track with forced flag + Language.
If no forced track available, the 'auto' stream will be selected.