I don’t know if your problem is the same as the one I ran into recently (some features simply did not work in our custom theme when accessed through https), and I finally tracked down the culprit in the header.php file (theme\common\header.php). I updated http://code.jquery.com/(older version number) to https://code.jquery.com/(new version number), and the lightbox and image display issues cleared up immediately!
I also found and corrected a ‘mixed content’ error by updating http://fonts.google.apis to https in the main.css file (theme\css\main.css).
Good luck!