So I emailed IHG (why not) spelling out that I want my credit (I know Chase is on the hook, but something else needed to be taken care of 2 in 1 email)
Here is their answer:
Moreover, with regards to your 20% discount, I'm really sorry but as per the program guidelines, the benefit could not be combined with another promotion. Since you already received the 80% bonus points, I'm sorry if the 20% discount could no longer be added.