Gameplay - Blinding Dart doing no damage to cannon minions

Good morning,

I've been playing Teemo in the top lane (insert satan comment here, if that's your thing), and while laning I've noticed that more often than not when I go to last hit a cannon minion with Blinding Dart it does zero damage. Providing you wish to take a look, it shouldn't be too hard to reproduce.

Thanks, Hammanu