When customers want to purchase more than one item - the items dissapear from the checkout cart

[nenad_hudek]

Hello Shopify Community,

I need your help. I have the problem when customers want to purchase more than one item, the cart becomes empty. As soon as they put another item, everything disappears. I am using the Sense Theme. In customization mode everything works fine. I tried it even across all web browsers like Mozilla, Safari and Chrome (Mobile and Desktop). Check out the mentioned webshop: www.photobottega.com 

Maybe someone has an answers to this issue.

Thanks in advance.