Folks at ZcashCo have finally issued an official statement on the whole Poloniex situation. Poloniex is second largest crypto currency exchange and they had disabled Zcash withdrawals and deposits due to wallet issues. When one opens the page for ZEC / BTC trading, a yellow warning banner with following text is shown.

ZEC is currently under maintenance or experiencing wallet/network issues. Deposits and withdrawals will remain disabled until a solution is found, which may require an update from the ZEC team. Any updates must be tested and audited before enabling.