I have used DVDFab to copy the disc 'Letters from Iwo Jima' to Vob files (Main Movie only).
When I play this I get the Japanese language and the English subtitles as expected.
I then go and do a conversion of this using the generic profile, and what happens is that the subtitles intermittently disappear. For example at approx 12 minutes two characters are conversing in a tent. The subtitles are showing only for one of the characters.....