Course freezing in iPad player

Hi, everyone!

I'm having a troubling problem with the mobile deployment of my Storyline course. We're testing a fairly complex course and having problems with one slide in particular freezing up. Every other slide works fine (the activity has three sequences you have to complete, and we're able to finish two), but this one just freezes immediately, and the timeline never loads-- even after, say, 20 minutes. Exiting and resuming takes it back to the previous slide.

Any ideas? I'm linking to the activity below.  The whole thing is part of a basic math curriculum for an adults-- this particular activity takes learners through the basic math you might encounter ordering at a restaurant. You can get to the frozen slide through the following sequence:

1. After the introductory dialogue is done, click the Appetizers menu
2. Respond to the first question successfully (the answer is 12)

After you finish step two, one of the characters will confirm your correct answer, and then... nothing.

Any help would be much appreciated! We bought Storyline in order to build activities exactly like this, so it's distressing not to be able to get it to work. :/

The activity is here: http://assets.gcflearnfree.org/testing/emobile/ioslaunch.html

And if you'd like, you can play it in your browser here: http://assets.gcflearnfree.org/testing/html5compliant/story.html    

You'll notice that the freeze doesn't happen outside of the app.

Thanks so much!