Lightbox makes page automatically scroll up

Recently added lightboxes onto a couple of my pages where the triggers are located towards the bottom of the pages. When you click a trigger and the lightbox opens, the background overlay scrolls back up automatically. So when you want to click on another trigger you have to scroll down again. Seems to work fine if you refresh the page, but I don’t want visitors having to do this.

Any advice for a quick fix? Thanks!