They hardcoded a nicehash server into their miner. Someone has to fork it to open it to connect to anywhere other than their own pool. Suprnova has an instance, but it’s out of date and behind the efficiency nicehash is revealing in their latest builds. Suprnova will be updating once nicehash releases it, though.
There’s the culprit: nheqminer/main.cpp at master · nicehash/nheqminer · GitHub