Your theme has a block of code that is highjacking clicks:
$('body').on('click','#header-outer nav .sf-menu a, #footer-outer .nectar-button, .container-wrap a:not(.wpb_tabs_nav a):not(.woocommerce-tabs a), .swiper-slide .button a, #slide-out-widget-area a, #mobile-menu .container ul li a, #slide-out-widget-area .inner div a',function(e){
There is a bunch of code under this, but essentially what is happening is that the section in the above that says .container-wrap a:not(.wpb_tabs_nav a):not(.woocommerce-tabs a) is capturing the actions performed on the Photonic thumbnails. This is preventing the subsequent Photonic actions from executing and you are being taken directly to the SmugMug page.
Short of changing your theme I don’t see a way to solve your exact requirement. However, you might want to consider an alternative where you are showing all photos from your album directly on your site instead of showing a thumbnail for the album as a whole. Examples can be found here. If you follow this approach, you might need to change another setting to get the lightbox launched correctly. If this is an amenable option you can give it a shot, and I will walk you through the next steps if you are unable to start up a lightbox.
