EntityDragon can not summon a final Jielong

[Emergency] I use the instruction block output in the normal world construction / summon EnderDragon summoned end Jielong, after summoning the map does not show the final Jielong not only blood but also changed is not an entity can not attack can not be eliminated, and now the final sector Long there is no way it can not be eliminated disappear, please help resolve this situation as soon as possible