Ekko Iceborn Gauntlet/Tiamat Bug

Syn: When playing as Ekko, your E does not always proc items (Sheen Items/Tiamat).

Was testing out Ekko to see if Tiamat would apply his passive to targets hit by the cleave (it doesn't) Then I noticed that my Tiamat/Sheen wasn't proccing all the time.

What I discerned - that if you have 2 stacks of your passive and E - Attack it for your third and your normal attack would kill it, your tiamat/sheen will not proc on it. Your sheen will stay active (count down on the bar) but will not proc (most notably was Iceborn Gauntlet never applying the aoe).

If your attack won't kill it, Sheen/Tiamat will apply as needed.

Steps to reproduce: Have Sheen/ Sheen Item (Iceborn is easiest to tell) and/or Tiamat Q a wave once it's in front of you. E Attack a caster minion that has 2 passive charges on it.

If the attack will kill it, bug reproduced, else build more damage until it will kill.

Where I believe this bug is high on the charts: If you are trying to get a slow on a group of people (W down obviously) and Iceborn doesn't take effect due to killing a target, iceborn will not proc until cooldown is reset.