Hello,
You have variable products and it does not use the Ajax add to cart to show the mini-cart after adding. Unfortunately, we don’t have Ajax add to cart option for the variable products in our theme, only for simple products. You may try third-party plugins to add the Ajax add to cart for the variable products https://wordpress.org/plugins/woocommerce-ajax-add-to-cart-for-variable-products/ or https://wordpress.org/plugins/woo-ajax-add-to-cart/
Regards