I just bought the LEGO set and entered the code, but I can't find the skin.(UPDATE: it showed up much, much later) I entered the code on my Mac with the same Xbox Live account, but it doesn't work. Maybe it only installed on my virus-ridden Kindle Fire that lags too much to use (the resource packs I bought didn't transfer from Kindle to Xbox, but that's probably a different issue...)? The skin is nowhere to be seen.

UPDATE: The skin actually was there, it just took 6,000 tries of opening and closing the store and skin selection to find it. It should have been there already...