Only preview showing in gallery page – not clickable

I made this site for my friend, and put a gallery on this page: https://www.vegan-chops.com/food-porn/

He went in and changed the name of the page and the featured image (which should have done nothing), then the gallery no longer worked. It shows up as just the one photo, and nothing more, whereas it used to be several columns and rows of photos from the gallery.

I went in and edited the page, deleting the original gallery icon from the page, readding it, making sure all the options were the same, and it hasn’t fixed it.

I’ve tried adding a new page with all the same settings and the gallery, but the same thing happens. What now?

Thanks!

https://www.ads-software.com/plugins/nextgen-gallery/