Mord Bug?
Q doesn't seem to go through when leaving the death realm, but E does. I just checked his E (Death's Grasp) it still affects the enemy champion as his R (Realm of Death) ends. The difference between these 2 are that E is technically a projectile that should have stayed in the death realm, Q (Obliterate) is a cast that's not a projectile and it stays in the Death Realm. It's like saying Sion's Q can be channeled in the Death Realm, but disappears as he goes out of the Death Realm. You can Q, Flash as mord and he is able to carry that Q hitbox with him, but you can't E, Flash.