The problem with “lightbox” effects is that these overlayed images don’t
have a URL, so you cannot share them. Instead, you have to create a
Page with a
[singlepic] shortcode, or select the “Show
ImageBrowser” option in the Gallery settings. When using the
“ImageBrowser” option, images will be displayed on their own, with a
unique URL that can be shared (instead of layering an effect over the
current browser window).