I’m afraid now, there is a setting wrong. Because you say “I don’t see Expander working’ and because I hear from owner of the site that lightbox is not always working.
In settings/lightboxes I cannot set Expander, so I chose Nivo Lightbox:
SwipeBox | prettyPhoto | FancyBox | Nivo Lightbox | Image Lightbox | TosRUs | Featherlight | Magnific Popup
In settings/Galleries I filled in the settings of Expander.
When I look at the settings/config of a specific gallery I see the red dot before Global (Expander).
The settings below adjust the configuration options for the gallery.
Global (Expander) Basic Grid Basic Slider Basic Masonry Expander
In my opninion the Expander lightbox is working on the page of the link in my previous post.
If I click on a thumbnail I see the enlargment in a transparent white overlay, with text on the right side of the image.