[GAMEPLAY] Smite not doing full damage

No idea how to attach a replay but I was in a game as Kog'maw jungle and my smite was doing about 1/4th of its listed damage. It happened about 80% of the time. I asked others to watch me as I smited and they all saw the same thing, that my smite was doing very little damage. I do have the replay saved, just have no idea how to attach it but if someone were to tell me I could very much do so. In the screenshot you can see that my smite did not do much damage to the large Krug