I have one project where my subtitles appear out of synch with the video when I zoom into the timeline. But after preparing the DVD they are perfectly in synch.
The subitle tracks are appearing correctly but the "monitor" window and the thumbnails in the timeline are still showing the swimming crab when actually they should be showing the mole cowrie, which appears about 4 seconds later than it should.
However after authoring everything appears in synch on the DVD.