Popup disappears immediately

When I preview the popup, it looks great. When I try it from a browser, the popup is supposed to trigger on clicking the ‘Take Me To The Pub’ button. It does in fact trigger it. I see it briefly and then it’s just a white screen. I have the settings set to wait for a trigger element (one of two buttons inside the popup) is clicked. I have cleared the cache multiple times, tried it in incognito mode, and force refreshed the site and nothing works.

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