Xerath close range E bugged now?

So does Amumu become untargetable when he bandages to you or is this a new bug? If you look closely I'm pretty sure you can even see that my character moves a bit to the opposite side of him before casting E and it still just goes straight through him. That or somehow his bandage makes him crawl so deep into my butt that nothing that I cast can touch him apparently without flashing away. How does this work?