Lightbox not loading

Hello. I have a problem. In http://vcelaritesin.cz/galerie/ after clicking particular image in the thumbnail, it keeps loading but never loads and open. It only work when im logged in the wordpress, not on the other PC’s or browsers. I tried updating plugin, republishing page, troubleshooting with Health Check & Troubleshooting plugin, but nothing works. What should I do?

Thanks
Sincerely

The page I need help with: [log in to see the link]