Hi
I'm new to Zen Cart but not to programming in general, and would like to share a thought on this problem that may bear some fruit (or not, depending on the root cause). I have read the whole of this topic through and hope I have understood the issue correctly. Egg on face is not my preferred dress code

One thing I have learnt the hard way, whilst coding with CSS/Javascript and PHP, is that in situations where there is not a strictly moderated structure for css z-index use and where there are many code contributors each with individual coding style, addons like lightboxes tend not to display on a rendered web page because of conflicting CSS manipulations involving z-index [css layers]. There will be no error logs for these in the PHP or Javascript consoles and you will tear out your hair before discovering that the lightbox is exclipsed by another module because of 1 of 2 situations:

1. The conflicting module operates on a higher CSS z-index than the lightbox and therefore hides it unintentionally;

2. The two modules have the same z-index which causes the interesting effect that, depending on which module renders its screen output first, leads to one or the other being eclipsed;

As far as errors go, these are presentational and not programmatic so will not lend themselves to tracing by logs if CSS layer conflicts are the root cause.

The result is the same in either case - so try to dig about in the javascript and CSS to see where the z-index manipulations are taking place and check that the lightbox has a higher z-index than the rest of the site. My own thought is that the CSS Mega Menu merged into Picaflor Azul's templates may be the contributory module as its z-index may be too high and cause the menu layer [which CSS regards as the whole display port] to be in front of the lightbox. Another potential culprit is the Social Networking Sidebar which makes use of CSS layers [z-index, interchangeable]. There are so many possible modules that could cause the problem.

A good technique to trace this type of error is to locate the z-index code for every module using CSS layers and make a list of the module name, pages affected by the module and the z-index of the layers in the module. Once you have done this you will be able to sort the list [use excel] by page and then by z-index and see if the lightbox is eclipsed by any other module with a higher z-index. You will then see what modules to adjust so that the lightbox comes out on top.

I hope these musings can help to locate the cause of the error, if not in your case, it will probably apply to other, similar, scenarios.

BTW: I apologise if there are any typos in this post, but my wireless keyboard batteries are dying and making it hard to type.