One other thing that comes to mind are the new performance options in Divi:
Let me know, if disabling one of those options solves the problem for you.
In case those options have no effect on the Popup behavior, feel free to hit the "Help" button on the right side and send us a message with the URL to your website. I can have a quick look at the website and let you know what I could find out.
Have a great day! Philipp