Can't add new Custom Link to Top Menu

I’m using Comic Press ForeBoding theme. On the Menus page (under Appearance), I want to add a Custom Link to the Top Menu, which I have done before. Now, however, when I click “Add to menu”, it endlessly processes it without ever actually doing it. I had the same problem with updating the right hand side bar on Widgets, but figured out I had to click “Screen Options” and then “Enable Accessibility Mode”. Is there something similar I need to do for Menu updates? I’ve looked around and have found nothing yet. I’ve also tried using different browsers with no results. Any help is appreciated.