Cart error

Hi!

I write because I have a problem with PPOM plugin.

I have a product and I add this product to the cart. If I add again the same product with the same options (size, color, etc.) I can’t see the +1 in quantity in the cart but I can see the price with both products.
I let you a link of my product: https://camisetasmartorell.com/producto/camiseta-blanca-impresa-todo-color/

Thanks,
Alberto M.