Iceborn Gauntlet not proccing on Graves' E

Mostly straight forward, though there's one condition. If while playing graves, you use E after having done one or two autos (that is, meaning you'll recharge with E), then using E will not give you the sheen effect, while it should.

Process to repeat : Play Graves, buy iceborn, level your E. Auto attack once, press E, you don't get the sheen effect.

Alternative : Auto attack twice, press E, you don't get the sheen effect.