Okay. What do you think is causing this? 

It might be something with your custom theme, @LadyJuse. Try switching to a standard theme temporarily to see if that helps.

The issue with that is the JavaScript is tied directly to the theme...

It's possible that something is missing or different with your custom theme that is present in standard themes.  Your custom page types have a very different page HTML structure - try changing your home page to use Header, No Header, or Splash as the page type.

I tried, and it didn't work.

I have done other pages with a similar structure to this one and they all work. This one even worked until recently...