Pretty much what happens is that armorstands wont get killed or tped even with @e[type=ArmorStand,r=2] when they are invisible and invulnerable, nor can they be killed in creative mode with a sword. This happend to me on a server because of a plugin (BetterShops) and the files for the plugin have been deleted but it still wont go away.
WAI. MC-66068