Yesterday I submitted a ticket to Poloniex...Let's see what they answer...
Dear Poloniex team,
it's been months since you have locked VCash deposit/Withdrawls.
You always tell it's because you need an update for the wallet. But this simply can't be true. Bittrex has no issues with xvc and they recieve the same wallet from the xvc team as you. So why are you scamming people this way!!!!?

??