I opened a new AA Citi Business MC on 1/12/14 and can see the 50k bonus on my February statement (closed 2/28). I just spoke with an AA rep who only gave me a generic "we don't know when Citi posts miles" answer. I figured I wasn't going to get anywhere with him so I politely ended the call.
I also have two personal AA cards from Citi which I opened last August, one MC and one Visa.
I've booked the outbound portion of a trip and need to book the return with that signup bonus, really hoping it posts soon.