I am facing the same issue using woocommerce. I update the QTY and I hit update cart and it goes to a blank cart page. I hit refresh and the product is still there with the Old QTY number. Same thing if I hit remove from cart. I hit refresh again and the item is back in the cart. The only way to remove the items is the clear the woocommerce_cart_hash cookie. Once that cookie is removed the cart stays empty.
The links that are clicked when the action is called is calling the CDN URL (www) not direct to the naked domain no (www). I have other woocommerce sites that aren’t using the CDN and they have no issues when going to the naked domain.
Thank you.
