Is there a miner in ethos 1.3.1 to mine CN Heavy?
If there isn't, please include it in the next update.
I've tried compile miners on my own and even try sgminer-gm 5.5.6 with no luck.
If any of the miners in their list have updates that support it, try sudo update-miners (or do your specific one). You can also install miners that aren't on their list. It CAN break ethos, fair warning, but it likely won't (still, I tend to do a full drive image backup before I install anything on active rigs).