New to Storyline: Playhead issue

Hello,

I have just started having the problem described here and found this post. No matter where I position the playhead on the timeline, once I press play the timeline starts at the very beginning. Likewise, if I pause the timeline and press play, it goes back to the beginning (as if I had pressed stop rather than pause). So, the only way to listen to any part of the timeline is to play the entire thing and wait for the part I want to hear. 

I have the latest update to Storyline 360, so I'm not sure why it's happening. I tried restarting the computer but it didn't fix the problem. The weird thing is that the problem is occurring only on certain slides. I'm not sure if there is some hidden setting that is causing this bug to occur on specific slides.