The unexpected behavior happens for orders with more than 1 item and for scenarios that at least one of the items have a delivery window that is not shared with other items, only one.

Example: Free shipping promotion with this restriction.

Cart: Item 1 - Delivery Window A, Delivery Window B Item 2 - Delivery Window A, Delivery Window B Item 3 - Delivery Window A, Delivery Window B, Delivery Window C.

In this case the cheapest option for the entire cart would be Delivery Window C even if is not an option for items 1 and 2.

The expected behavior would be to consider the cheapest options that are actually available for the entire cart.

1. Create a free shipping promotion that have a restriction "Only apply discount to the cheapest shipping option";
2. Add to the cart items with common delivery options and a item with a different one that is not applicable for the other items;
3. Check that the promotion will set a free shipping for all the items except the one with a different delivery option.

• Enable the different delivery option for the other items on the cart;
• Remove the different delivery option for the item that the promotion is not being applied correctly;
• Remove the restriction flag "Only apply discount to the cheapest shipping option".