Fotomagico 6: Slides ‚stuck‘, next slide not showing

I am composing an extensive slideshow in Fotomagico 6 with 500 high res pictures on my MacBook late 2013. After a crash I am experiencing problems with the automatic transition from slide to slide. After a specified time (e.g. 5s) the next slide should appear. This is sometimes not happening and the slide is ‚stuck‘, also with the animations going on indefinitely. This fault can be reproduced but is not limited to specific slides. Reinstalling did not help. Any advice? Thanks!