I totally forgot, refreshing the page often fixes it, but then it usually shows up again on a subsequent refresh, so I guess I should have instead submitted it as a bug. Will do now. Thanks!
From Bubble Support: “So it turns out that the buggy behavior is due to the animation. It’s on the list of things to fix but it is not a priority. The thing for you to do is to take off the animation and do a standard show action of the popup. That will fix things.”