I think this is an issue only in editing. Playback of the entire slideshow from the beginning seems to be working.
I have a MP3 file of approximately 12 minutes, 180 slides of varying duration with 4 markers to sync at specific points.
If I select slide #129 or lower and press spacebar for playback, the music starts at the appropriate place and stays in sync with the slides for the remainder of playback.
If I select any slide beyond #129 the music playback starts at exactly the same place (about 8:45 into the soundtrack) and plays until the end of the track (8:45 thru 12:00).
For reference, if every thing worked as planned slide #129 would be showing when the 8:45ish time happens…
Seems like there is a pointer or index issue in PhotoMagico that prevents the music from being started with the correct offset…