Popups not opening correctly

Seen this error on a couple of sites I’ve built but only now been able to isolate it to this plugin…

You’ll see on mobile view on this site I have an icon for the menu generating a popup. With oohboi disabled it opens correctly as a popup but if I enable the plugin it does not, instead it adds the popup content to the very bottom of the page when clicked?

Very strange and I can’t find any other mention of this issue, but it definitely works when the Ooohboi plugin is disabled and stops working once it’s enabled.

Cheers
Ste

The page I need help with: [log in to see the link]