Photo Gallery thumbnails blank

Bare with me, I had someone put the site together but he has recently disappeared lol, and regardless most of my posts have been through trial and error. but anyway..

I’m trying to add a photo gallery onto my page, but the thumbnails show up blank when it’s posted. I’m not sure what I am doing wrong, because there is another page that has a gallery up showing the thumbs (but I didn’t post that one)

Sorry if this is very vague, if more info is needed let me know.
Thanks

Here’s the link to the page with blank thumbs: