Image holder showing in product category

HI,

I’m adding products to one of my product categories, however, the page is showing image holder with 12 pics gallery, as well as showing individual products.

It only occurs in one of the product category (with 12 products), other categories so far are fine ( i haven’t added more than 12 products yet for other categories). I’m not sure will same thing happen if i add more than 12?

How did it happen? I just want the individual product listing but NOT the image holder.

Thanks for your help.