I've just now created a new support ticket with Poloniex regarding withdrawals, reaching out to them with an offer of assistance in resolving the issues people are having receiving their funds.
In the first instance I'm asking them for log files, latest block info, peer node info, etc. and given how long it takes Poloniex to respond, it might be a while before I can post an update here.
After that I'll need to somehow resolve the issue which will take a little longer so please be patient, even though you have all waited quite a while already!
But I will keep this thread informed as/when I have news!