Yesterday I did send some XEM to mine Poloniex account but the coins still didn't arrive in mine wallet, since today they show the quoted message when you look at the XEM market and their wallet is disabled.
XEM 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 XEM team. Any updates must be tested and audited before enabling.
Any information about this would be appreciated since I don't hope that mine coins will be locked for a long period.