In certain areas (namely the upper floor of the Ebonheart Chateau) the new "Hew's Bane Rug" is having layering or clipping issues of some kind. I make a quick 60 second video demonstrating this:
I have ran into the same problem. I have Ravenhurst and the carpet works fine upstairs! But as soon as I place it downstairs it disappears. I don't want it to cut my feet off so I haven't even placed it "above" the floor..