Relume Gallery 21 - CMS Slider: Lightbox not showing on published Site

Hey, thanks for your prompt feedback. I struggle to understand how this should work with yet another JS from Sygnal. it seems outdated, if I correctly interpret the cloneable. Why does it work in preview mode in my build and NOT in the published site? What does Sygnal do in this respect? Would love a step-by-step guide for my specific build, if possible.

Thanks a lot
Gerd