Bone Manipulator appears to be broken

Hello, I’m attempting to use the bone manipulator tool on a standard HL2 NPC, but when I select the NPC hitting the C key, then right-clicking and left clicking “Edit Bones” it doesn’t enter the bone manipulator showing me the bones or any of the arrows. I’ve tested on every NPC, even some custom models using HL2 bones, but no luck. Any one experiencing this?

I am, yes.

Bone editing is supposed to be working, right?