Graves' E sheen bug

Tested this without fail in practice mode after noticing it in-game when I bought an iceborn gauntlet on him.

Sheen does not activate on casting graves' E unless it is the FIRST shot after reloading. So if you basic attack, then cast E, sheen doesn't activate. BUT if you already have two shots loaded and you cast E, sheen activates. Easy to test - buy iceborn gauntlet and shoot at a dummy in practice tool, or trinity force and watch your active buffs for sheen to pop up or watch to see if it goes on cooldown.

This bug sucks because usually you want to shoot before using your E to cancel your auto attack animation and postpone reloading by one more basic attack. Sheen works on the rest of his abilities just fine.