Most skins also show if subtitle file is loaded.
What does skin tell you?
Some suggestions:
Check if "Auto position" is selected under
rightclick > Subtitles (
*) > Subtitle properties.
(
*: whilst doing so also check if "Show subtitles" is selected.)
Other settings which may make a difference are those under
rightclick > Options > Preferences > Subtitles (e.g. Subtitles should not be disabled and you may try "Draw subtitles to Overlay surface").
And (to make life easy) you could also try a different setting of overlay mode under
rightclick > Options > Preferences > Video > Video rendering
Perhaps also have a look at
this post/thread (click here) 