Iceborn Gauntlet doesnt proc passive with Evelynn [GAMEPLAY] (patch5.12)

Was playing a game with the new patch 5.12 as Evelynn and bought Iceborn Gauntlet. Unique passive spellblade would not proc after using an ability.

To reproduce:

1. Join a normals blind pick game
2. Pick Evelynn
3. Buy Iceborn Gauntlet
4. Use an ability on an ememy
5. Follow up with an auto attack to proc the passive.
6. passive will not proc

It did proc every now and then but I would say that %90 of the time the passive did NOT proc. Hope that helps