I'm trying to set up a character rig and managed to get the entire body working alright, it has IK constraints set up and all that. Each section of the limbs is segmented (and also a separate object) which is all parented to the armature.
The head consists of just one bone that's connected to the neck bone. The head bone copies the rotation of an IK controller that influences the neck bone.
I started trying to rig the face. I added in two bones for the eye brows and parented them to the head bone. When rotating the head with the IK controller, the bones follow along perfectly.
To get the head mesh to deform, I added the armature modifier to it. After adjusting the weights, this worked perfectly. So now when I rotate the head IK controller, all the bones follow along perfectly, however, I end up with the head mesh deforming from the eyebrows as though the eyebrow bones weren't moving.
The eyebrow bones are the only bones with the "Deform" checkbox checked, though I went in and checked weights for everything anyway and didn't notice anything wrong.
The rig in edit mode:
The rig in pose mode:
The unwanted deformation:
The deformation happening even with the central movement bone:
What have I done wrong, and how do I fix it?
The .blend file:
