Hello,

Yes, as we can see it works differently on the single product page, and yes, these mechanisms a bit different. But we don’t know why it firstly shows USD and not the current currency. By default, WooCommerce doesn’t have an AJAX adding to cart function for the single product page and that is why WPML may work wrong. You can disable this custom option in Theme Settings -> Product page since we are not able to change anything in this situation. You can try to contact WPML with this issue also. If there are some requirements from their side, we will help you to implement them.

Regards