I am in the same boat (pun not intended!).
Bought the AARP gift card. Yes, I booked thru a TA and she was unable to apply it. Sent the info to the "Shared" email yesterday, hoping for the best.
I have no problem applying it for OBC once onboard. People can do that right? Use the AARP ones onboard at GS? Even tho I booked with a TA?
Boy, it's soooo easy with the Carnival ones...