I tried to implement a fancybox (fancyapps.com) onto my homepage to display a form. The modal wouldn't appear when the call to action button I set it to appear on is clicked. After deactivating all my plugins, the modal worked.
I then re-activated each plugin one-by-one until I found out which plugin broke the modal. As soon as I actived Google Analytics for WordPress, the modal no longer appeared.
No errors are being outputted to the Chrome console window, which is odd.