I have the same problem, i didnt recieve my ETH deposit and waiting now for 11 days. I dont know what to do, they dont answer on e-mail, tickets.
I send ETH to Poloniex from OKCoin, right now I checked my account on OKCoin and they refund me money. It was their fault, because they wrote address with CAPS.
Again poloinex has nothing to do with the execution of your transaction, if the transaction is ongoing and a problem occur during the mining then your ETH did not successfully transfer to poloinex so your poloinex account did not recieve any, please be knowlegable about things before trying to trade in exchange sites because trading is not like gambling its more complicated than you think, gather some information its for your own sake.