Smite not working

Keep in mind this is the so there's no way i smited the player.

https://gyazo.com/75d7dd334f160300022e3edfe7bd7d80 As well as in this Clip doing 410 damage and the other doing 570,

In the level 2 clip the Smite does 410 + Zac W and it did no damage my Auto + W + Auto would have killed blue making it a level 3 vs a level 2 . In the other clip did 570 damage and did not actually go through to the buff. Not sure how i can recreate this but is definitely game breaking if it were to happen elsewhere.