Hi Bartosz, I have created two test sites (and given you full admin access in a PM) so you can troubleshoot this.
(I removed the HTTPS part of all the URLs, since the first time I tried post this, it “ghosted” from too many links, I presume.)
prettymuch.biz/sites/dfactoryB4update/
original site, latest versions on everything, except:
Responsive Lightbox v1.7.2
Responsive Lightbox – Justified Gallery v1.0.6
Responsive Lightbox – PhotoSwipe v1.0.4
prettymuch.biz/sites/dfactory/
exact clone of original site, with these updates:
Responsive Lightbox v2.0.3
Responsive Lightbox – Justified Gallery v1.1.0
Responsive Lightbox – PhotoSwipe v1.1.0
(by the way, I had to update the two add-ons manually, as I received “unauthorized download” when I tried to update from WordPress admin)
If you go to prettymuch.biz/sites/dfactoryB4update/kitchen-remodeling/ and click on any of the images, you will see it filling the page in the lightbox overlay.
If you go to prettymuch.biz/sites/dfactory/kitchen-remodeling/ and click on any of the images, you will see the black overlay, with controls, but no image.
I have done my testing on a Windows 7 PC, with the Chrome and Firefox browsers (latest versions)
However, with Internet Explorer (v11) the lightbox doesn’t launch at all.
With IE, clicking any image on prettymuch.biz/sites/dfactory/kitchen-remodeling/ has no effect
Furthermore, with IE, even images in galleries (which correctly launch/display the lightbox in Chrome/Firefox) will not launch the lightbox.
I have browsed through the documentation and taken the product tour, but don’t see where I would have to change any settings from the RL v1.7.2 configuration.