base layer not showing in quiz review

I'm creating my first storyline project and having trouble on the quiz review.  It won't show my base layer (with the question, user answers, etc.)

I've searched the help and support discussions.  I found another user who posted about the same issue 2 months ago (using the same subject line), but if a solution was found, it was not posted.

I'm attaching the file and hoping someone can help me figure it out.