I've been seeing cards posted on Mut.gg that are not showing up in the Auction house.  I know its not a time delay issue, as I just saw a card posted on mutt.gg, which i couldn't see in the AH (even filtered by position/name/rating), and after seeing this card on the website and refreshing continuously for a few minutes, I final saw it as recently sold "6 seconds ago".  This has been happening pretty frequently as of late, and I don't remember an instance of this happening prior to this month.