I converted the Blu-ray subtitles using BDSup2Sub, and DevedeNG got an error. Somebody said you are trying to use a text based subtitle file. I doubt DevedeNG is converting it to a text subtitle file.

DVD Styler gets the same error.

You have to encode the video using HandBrake, and burn the subtitles into it. No way to disable the subtitles though. They will always show.