I have Poloniex account but never used it for STEEM/SBD. I always use @blocktrades. Last December I experienced 17 days delay in BTC with Coinpot. I just waited for it to arrive. I guess it would be the same. As long as we put the correct address it will go through, just delayed sometimes. :)
RE: Steem deposit to Poloniex. It has been disabled and my steem is stuck!!