Hmm, to be honest we don't have any S9 to test so we can't tell for sure. But it would be highly unusual that it would not work. Can you please post a print-screen of the first page of Antimer tab System / Overview?

And can you please configure your Antminer S9 with a separate Bitcoin address
(so that only this miner would use this Bitcoin address) and leave it mining on NiceHash for approx. 15 minutes? Thanks.