Why estimated earnings on Suprnova are very low?

[wilkas]

For the first time I've tried to mine on the pool instead of mining with Nicehash miner, because I need a bit of ETH to transfer some tokens from my ETH wallet. I'm using RX480 for mining (Claymore miner shows ~20,5Mh/s). I've joined when round was about 23%, now it's 60% and my estimated round (83h) earnings are just 0.0013 ETH. Am I doing something wrong or is their estimation buggy? Nicehash reported higher income when mining on the exact same algo.