How can you tell that it is an altcoin block that was found? They are bitcoin miners, right? I am using the bitcoin stratum. I am confused.
Best Share = 753,489 => not high enough for Bitcoin => must be an altcoin.
When you mine with nicehash, you are being paid for shares by somebody else, who has some control over what work is being done. You could be mining on any SHA256 based cryptocurrency. It makes no difference to you as the payment for your shares is made by Bitcoin.