From what I knew, CCMiner was for nVidia primarily - however if you can advise on the settings I will definitely give it a try as EthOS doesnt give much example for CCMiner or its config.
The settings is actually 2 parts, the top part being the local.conf and the second being the sgminer-gm-xmr.stub.conf file. However I have tried not setting anything in either the local or the sgminer and it didnt make any difference!
BTW I have AMD 580 on the rig if that makes any difference.
I added the tag #xnsub and the miner didnt start even after 5 mins. However I didnt mention NiceHash recognises the rig however hashing is 0.
You may be right, all my gpu rigs are Nvidia so...
The other two settings should be the difference though, they aren't tied to the specific miner. I did not need to alter anything other than my local.conf. I'm afraid I can't be of much help with the specifics for 580s, but Ethos is set to be pretty plug and play, so I think your problem may lie in the local.conf and Nicehash playing nice.
I have been having this issue over the last 3 days. I have tried USA, EU, HK, JP pools and all are the same for me.
FWIW, Nicehash says I keep connecting on the BR pool, even though the USA pool is closer and my proxypool1 (BR is 2).
Also don't monitor Nicehash so exactly. I have often had completely ridiculous reporting from it (from double the possible hashes on an L3+ to zeros on a working farm); base it on daily payout.