Pdfs and Macintoshes

I have built a project that has a number of pdfs associated with it. On a Windows machine, it works fine. When I try it on a mac (MacBook Pro running Safari) When I browse to a pdf it comes up fine, then I can’t browse anywhere else. The TOC pane looks functional (books open and close etc), but doesn’t actually work. I don’t go to another topic. I can use the back button to get back to the home page, but otherwise, I’m stuck there.

Any thoughts?