@davebogan98 After I reported it, WIX still hasn’t fixed it (1st April 2022). Maybe you could report as well. See if more people reporting will work.
The solution above is correct, and able to pass data between (or use memory to save data). But if I want to switch forward and also backward between lightboxes, it becomes complicated.
At the end I use the “Multi-state box” element instead of lightboxes (put a Multi-state box in a lightbox), as it can switch between “states” easier, and save data in the same page. Plus it is faster to load between “states” than between lightboxes.
So the solution I use is a mix of above code if I really need to switch between lightboxes, and “Multi-state box” for continuous lightboxes.
“Multi-state box” is in EditorX, and I believe “slideshows” is for WIX editor.
I wish WIX will fix the bug so it can go back to the way it was, which is easier to code 