Aggravated enderman stop becoming aggravated when they can't attack the player that they are aggravated at

If you aggravate an enderman and get into an area where it can't attack you, for example a 2 block tall roof above your head or if you stand 3 blocks above the enderman, it will stop becoming aggravated after 20-30 seconds. This is a major issue as it makes it a lot harder to kill enderman and therefore, harder to obtain enderpearls.