i made you a screencast. This shows first an actually site with a Lightboxt that works. Than i switch to our new site and there to the Lightbox that make the problem. very strange is, that the left graphic works if i click, and the right not. booth graphics are .svgs.
And when you open it in safari, the left graphic will displayed correct. if you test this in chrome, no graphic will displayed after i click at the left graphic.
booth graphics are 800 x 800 px, but in my new Lightbox webflow shows a size from 150 px to 150 px.
At the first Lightbox ( old site ) the graphic size will display from 800 to 800 px.
I hope that helps. Can i Share you our site as a private mail?