** Edit: There was a variable saying to pause timeline at cuepoint 5, the cue point was way past the end of my timeline and caused the bug. I deleted the cuepoint and the variable. It works now. **
I have a slide for wich the duration of the base layer is 20 seconds. But when I preview in storyline or in Review, the timeline is way longer... if somebody had this problem and found a workaround, it would be really helpful.