I have not enabled any free shipping discounts (no conditions set for order amount, shipping zones, or products), but I still encountered one specific order where the shipping fee was $0. (Other orders are fine) Could this be related to the incart.php bug mentioned earlier in another post?
I would like to add one more point: this order does not seem to have applied any free shipping discount. Normally, regardless of whether free shipping is used or not, the order should display the customer’s selected shipping method.
However, this order is different — it did not show any “shipping method” at all. The order confirmation email I received also did not display the shipping method. (In the admin backend, the shipping method is shown as “other.”)