Hello,
first off, I love this plugin and have had it work for us wonderfully in the past. I recently setup a new site and found your plugin not working (even with the default Twenty Fourteen theme). I disabled all my plugins and it still did not resolve my issue. Here is my issue:
I click on an image, it starts loading as though it is in the lightbox (i.e. there is a spinning wheel in the center of the screen. Then all of a sudden, the wheel goes away and the image opens up without lightbox giving me a image url in the browser address bar. I looked in the Chrome console to see if there was anything breaking and did not notice anything that would cause it to break.
Has anyone ever come to you with a similar issue before?
Running WordPress 4.0 with default WP theme and no other plugins installed.