Modal overlay issue/borkage

I’m having issues with modal overlays, which I believe is the term that’s used when it comes to those dialogue box doohickeys that appear, usually when you want to add a link

What happens is that when I go to add a link on some pages it produces the add a link box, but it won’t allow you to write in the link box. It’s like it’s locked. You can force your way around it by right clicking into the text box and pasting it in. produces

The one you’d be able to see it at is here – try adding some text into the box and then linking that text – it won’t like it.

This seems to be happening on our add your business page as well, which isn’t too clever. Can anyone help?

What I’ve tried:

I found an js error in the popover plugin popover, but when I tried deactivating that to see if it helped it didn’t solve the issue.

I also tried deactivating tinymce advanced, but no joy.