Hey @seun, I’ve done some digging here and this does seem to be a known issue. Similar to this thread here Product DiscountCodeApp Codes Not Working With Draft Orders
From what I’m finding this is not yet resolved. I would like to attempt to replicate your specific scenario though. Can you share more details on the kind and type of discount this is?
If you use draftOrderCreate with the discountCodes, do they apply properly?