Found the conflict. It’s this jQuery plugin: https://github.com/codler/jQuery-Css3-Finalize
Removing it fixes Responsive Lightbox. Luckily, we aren’t really using it anymore. Might be worth trying to figure out why it conflicts though, or at least making a note of it in the docs somewhere.
How to Get Support
After you register and login to the site, you may post all plugin support questions in the Support Forum.
If you need to provide private info, please create a ticket and then reply to it using Set as private reply option.