Free shipping with a purchase threshold
Hello, When a vendor sets a threshold of $100 (for example) in order to receive free shipping and a buyer uses a prepaid gift card (not a coupon) for $50 it reduces the overall cost they must pay by $50. Currently with your plugin the gift card is acting like a coupon and when the price is reduced by $50 then the vendor requires another $50 to be purchased in order to receive free shipping. This should not happen, as a gift card is like cash and a coupon is just a discount the vendor has offered in their store which would require the buyer to purchase up to the threshold in order to receive free shipping. As it stands now your plugin is only operating as glorified coupon even though customers can pay money to purchase a prepaid gift card to give to another person. Your plugin only works properly if there are no threshold purchase rules that have been imposed by the vendor. I really hope you can fix this soon.
This issue was in result with woocommerce functionality while it have been fixed by woocommerce where they now provide you option selection for choosing either the coupon should be applied before shipping or after shipping.