You are using an automatic discount which gives the customer a discount when they have two items in the cart. eStore has a check to make sure people don’t add items in the cart to get a discount then remove the item. Can you see how this can be used as in exploit if not guarded properly? When eStore detects this it will empty the whole cart to prevent users from scamming the system. Bottom line, your customers are not allowed to remove items from the cart after they apply a discount.