That's very odd. Are you positively absolutely certain it's not there somewhere? You cannot be mistaking it for another card? Do you have so many cards that the new one scrolled off? Have you tried accessing your account using another browser? How about the mobile phone app?
I finally called. They were able to add the card, but I couldn’t understand the reason given for its absence (strong accent of agent). And no it didn’t scroll off and I did check in difference devices. It was all very weird. At least fixed now.