These accusation with Poloniex are really making me feel worried because I also have a couple of funds deposited on this exchange site and I'm afraid I might also encounter the same problems as most of you have. I still haven't tried withdrawing my investment on Poloniex because I was thinking I am going for long term for these coins and probably check after a few years but I might be having problems when withdrawing by that time.
The value of the funds they won't credit me is now in the region of over $80,000 so there may be no other options available than to hire a lawyer.......
It is always good to withdraw your funds when you book some profits. From last year onward many people are complaining about the deposits and withdrawal, better ask the support twice that you need your money back from poloniex.