[GAMEPLAY] Ez Q Doesn't proc Luden's Echo passive

So I was trying Ap ez today and decided to get Luden's Echo on him. But it didn't seem to proc the passive when I used Ez Q. Is this a bug? Or is it designed so it wouldn't work for his Q? Because his Q still counts as a spell, and I just find it weird that it doesn't proc Luden's Echo passive. I've tried it a few times to see if it was a one time thing, but Ezreals Q doesn't proc the Items passive.