Discount Code Error - Eris Morn Papercraft Mask Set
I unlocked the 3 Bungie rewards for FOTL 2019 (emblem, Eris mask, and Braytech Werewolf shirt) and redeemed them all right after one another on the rewards page. I then got the email for the 3 rewards (a link to the emblem unlock, a link to a discount code for the shirt, and a link to a discount code for the mask). I used the shirt code and purchased the shirt. I then tried to place a separate order for the mask, but the discount code isn't working. I'm getting the following error message: "This code isn't valid for the items in your cart."
What are the next steps I can take to "purchase" the Eris Morn mask?