Similar situation here. Bought 1 ETC on Polo, created deposit address and started mining on Suprnova. So far I've had 6 payouts over the past few hours and none have shown up yet.
you can check your transaction ID's in "My Account" -> "Transactions". Send them to Polo so they can look them up, they're all confirmed from my side.
I think the hang up is on Polo. I noticed that payments hadn't posted for quite some time on Polo for me after they were sent. Maybe related to the transaction volume or something, but clearly took longer than I expected.
Thanks ocminer and longsnowsm. I'll take a guess that they're just backlogged for now and give it some time. If it's not resolved soon I'll go transaction ID route.