Because I rebound it to my number pad which is most comfortable for me as it is closest to many other keys I have rebound. Not everybody plays with the same key configuration... and I'm one of the rare ones that play on the right side of a keyboard.
I did temporarily moved it back to E for testing and yes, that does work as it should. However, because they gave us the option to rebind our keys, I assume they intended for that function to work with whatever key that it is bound to.
So perhaps this is a small bug.