Same thing is happening to me right now. Sent 1.003 ETC, poloniex shows my balance as zero. Then sent another 0.1 ETC just to be sure I'm above min deposit value, and despite gastracker.io shows my balance just fine being 1.1011 ether, poloniex still shows zero. It now has been 4 days 6 hours as my ticket being processed...

https://gastracker.io/addr/0x4231ca8b8de5df4cdbc68174359f186d522d3964

Both transactions are way above 20000 confirmations right now.

These one were test ones, I'm just happy I haven't sent more, thought I still want my 20 bucks back =P.