Not letting me add discount code tile

I’m trying to add a discount code to a tile for a specific event we’re selling at this weekend. It’s a buy X Get Y discount. If I add the items in the POS app then add the discount manually, it works perfectly. But when I try to add it as a tile so I can shortcut it, it is telling me its an invalid code.

I had an inkling that that may have been the case, just wanted to make sure I wasn’t mixing something. Changed it out for a hard $ discount equivalent. Just launching our product at a swap meet this weekend, getting everything lined up!