In-game Item not working, Poacher's Knife not activating after smite/kill (large monster)

I was doing a few test rounds in a custom game with Evelynn using Poacher's Knife and realized that it was not activating or resolving the effects after I used smite on a large monster. I used smite as the killing blow and it still did not work, and I also used it early on vs the monster then killed it afterwards and it still did not work. I have been testing the Poacher's Knife in 4 different custom game. I used the upgraded version and still does not work. Also I have only seen the effect resolved once when i used it on the enemy's red jungle camp. I have tested the active ability on dragon and all the larger monster with the exception or Baron and it does not activate 1 out of 12 times X 4 games.

Please fix, as I need it desperately to farm through the jung and calculate the amount of time I can do my rounds and see how cost effective the item is with in a specific amount of time between ganks.