blatantly wrong. any buyer can see their wallet transactions on the block chain. And I can clearly see 50ish withdrawls from my nicehash wallet between 2017-12-06 02:27:00 and 2017-12-06 06:15:12 averaging about 1btc each.
If you are checking your addresses on from Nicehash, you won't find it, its because they are using internal addresses from their site, and you can't find them on Blockchain at all