This may not be a bug but I found it annoying. After killing all of the vampires at the end of the Dawnguard quests, every item in the castle can only be stolen, books, ingredients, weapons, etc. The only things I could take without stealing was what I found on the vampire corpses. Another thing that bugged me was that the big chest in the room where I killed Harkon was empty. Zero loot. Harkon's remains had some stuff, but I was hoping for a little something more to fatten my coin purse.

Well if you side with the vampires you get your very own bloodstone chalice