Hello Bartosz,
When a page is viewed in IE v11 and an image is clicked there is no response whatsoever, no lightbox overlay, no photo displayed, nothing. This behavior is the same for my Windows 7 desktop and my Windows 10 laptop. Problem occurs for every one of the seven sites I tested where I use Responsive Lightbox. These seven sites work as expected in Chrome, Firefox, Edge, Safari (on iPad)
To demonstrate the problem, I have created a minimal test site with one page:
prettymuch.biz/sites/photoswipe-test/gallery/
Configuration:
WordPress 4.9.7
Twenty Seventeen Version: 1.6 theme
Responsive Lightbox & Gallery v2.0.5
Responsive Lightbox – Justified Gallery v1.1.2
Responsive Lightbox – PhotoSwipe v1.1.1
SG Optimizer v4.0.7 (Performance optimizations by SiteGround hosting company)
Server running PHP v7.0
What confounds me is that your example page, dfactory.co/products/photoswipe-lightbox/
does work in IE 11. Perhaps your example page is still on Responsive Lightbox v1.7.2?
I will send you access and login credentials in a private message.