It's prob just not be reported or a typo but item descriptions say when a monster killed that u used smite on dies you get the buff, However You don't have to kill the monster I've noticed just smite it and run away.
i believe this is intended. it makes invades more interesting... lets say you start gromp as jungler. you initially smite it to utilize that passive it gives (like thornmail). then the invader can come and smite it away. now you realize that in the future, you have to be on your toes about invades because you realize, sometimes you cant just smite it right away or else the enemies can easily grab it.
