Kennen - Using Electrical Surge (W)

I haven't quite nailed it down yet, but there's a bug with Electrical Surge (W) on Kennen and I can't even say for sure whether it's always been there or not. With my much increased play time with him, recently, and harassing in mid lane, I have noticed that this ability will sometimes not strike the enemy player when used (when in range and tagged with a mark of the storm). Now, in the times that I have seen this happen, there was a minion (or more) that was tagged by mark of the storm also. While I could not say whether this was a symptom of the cause, I have noticed this being the case in the handful of times where this has happened. Also, the Marks of the Storm may or may not have come from different ability sources (i.e. from Q, from E, or from a charged W auto-attack) on different targets. I want to say that I have even seen this once, yesterday, happen even between just minions (though using E through all minions and then using W has always seemed to strike all targets affected, which again leads me to believe that this bug comes from marks from different ability sources, a range difference to targets with marks from different ability sources, or a difference of a specific ability source). I couldn't even begin to tell you whether this happens during Slicing Maelstrom as there's just too much chaos and ability usage during these.

An example case where this happened for me: I was in mid-lane, harassing an Azir player, and used Lightning Rush (E) to rush at him through minions. After getting into auto-attack range, I throw the charged W auto-attack to mark the Azir player (the attack lands and he is visually marked). I then waddle back into a safe distance (still in range) and hit Electrical Surge (W) whilst standing next to a minion also tagged. The Electrical Surge only strikes the minion(s).

Thought I'd mention it. Thanks again for everything. Ysoh -