First, "Be Concerned".
Second, "Make sure you submit a support ticket, from a Polo Freshdesk account with the "same email address" as the account you are having trouble with. If you submit it from a "linked" account, even if it is your "main" one, you can expect to be ignored.
Third, "Move your accessible Crypto off of Poloniex". Use a different exchange, such as Bittrex or Livecoin. Polo's interface is more functional, but their support has been virtually non-existent.
Fourth, "Give the Second suggestion above a week or two. Hopefully you'll have a positive outcome."
Fifth, If you "must use Polo" only use Polo with small amounts of virtual currency. If your deposits or withdrawals are worth $2000 or more, expect to have them get stuck without a word from them, and without any action until you complete the Second suggestion above.
Finally, here is a telling of my experiences with Poloniex, and reason to be concerned:
https://bitcointalk.org/index.php?topic=2142453.0