Cred — Cashback for Citi card offer

I did a payment of 702 via Citi Card on cred pay under flat 100 cashback offer. I saw the cb offer getting applied correctly. However, I didn't get any scratch card or Cashback after completing the transaction.

Cred support says it was a bug and they can't offer cashback on the same. I would not have done this transaction if this was known and cashback wasn't shown on payment page.