Customers having problems adding more than one item to cart.

Customers can only add one item to cart. When they add more, it always goes back to only the last item they added. It only happens on Desk top view. It works fine on Mobile view. I edited it, previewed, and I did not have that problem. I went to the site as customers do, and it happens every time more than one item is added. Can you go to it and check how it does for you? Not in the preview, but just going to the site as a customer does. Thanks for any help you can be.