I have found one more thing that it would not add another item from the cart i.e. order in woocommerce displays only the first item from cart with pending payment status with 0 amount value, it does not have _pos meta tag in order and also the order amount related tags like _order_tax and _order _order_total are having 0 values . So i am assuming it is breaking some where when trying to add another product or just while coming out of adding the item and calculating the order amount based on items. Can somebody help me where i may have to look in to ?