Attack Speed Proc Bug with Runaan's Hurricane

I'm unsure if it's a bug with Thresh or with Runaan's Hurricane in general, but if you go with an attack speed build and use that item, it reduces your attack speed to 1.0 while it applies the proc, regardless of your current attack speed. In a bot game a second ago, I raised Thresh's attack speed to 2.37 with that item as my last upgrade; when I was 1v1 against a bot I had 2.37 attack speed, whenever I was in range of minions my attack speed was hilariously reduced.