Firstly, I apologise if the issue has already been raised.. a search didn't find anything relevant.
I am using Xara365 level 12.6.2.49603

I have come to what I believe is a bug in the way pop-up layers behave with different browsers. I have created new pop-up layers on a website that I'm working on. The pop-ups are designed to appear in the page area below the current content, some requiring that you page down the window when browsing. All pop-ups are designed to slide up from the bottom and are checked to automatically close. Although they display correctly, as soon as you use the slider to pan down the window on the browser they abruptly disappear. The curious thing is that this happens on Chrome, Firefox and IE ver11, but does not appear to be a problem for MS Edge. This result is also consistent in the browser previews. Is this a known bug?