Please share your site url.
So that i can check and let you know the exact solution here.
Please Share screenshot
It's the small thumbnails on the right side when you click each product. We'd done half of the products manually, but we would love to code it so that when we need to add more, or change things, we don't have to do it manually. It's because we used .png files with transparent backgrounds instead of .jpg.
Hopefully there's a code for this.