unfortunately poloniex has not allowed withdrawal of steem/sbd for a long time now, which is one reason steem/sbd value has been on constant decline recently - the only way out of poloniex for steem/sbd holder is to sell it, and nobody wants to buy there because no sign is given it will be fixed any time soon.

looking here: https://coinmarketcap.com/currencies/steem/#markets
I noticed poloniex always has the lowest steem/sbd prices, and sadly all the other exchanges are following behind that constant decline, so not only is their security flawed but they have been undermining the value of our currencies by not allowing withdrawal and forcing people to sell.