Land Dreugh's will engage in combat, and will do a 1-2 lunging attacks, but then will just stand there and stare at you indefinitely. They'll keep following you and combat music will still play, but won't do anything apart from that until you kill them. Every Land Dreugh I've encountered does this, indoors and out. I'm not sure if this is a bug from the base game or brought on by the patch. I do not have any mods installed that alter NPC behavior.