Strange behaviour with Vector3.Lerp between two bones

I have this code:

public void HitboxUpdate (CapsuleCollider collider) {
	Vector3 center = Vector3.Lerp (anim.rootBone.position, anim.headBone.position, .5f);
	collider.height = (anim.rootBone.position - anim.headBone.position).y;
	collider.transform.position = center;
}

meant to displace and scale a character hitbox according to a position inbetween the root and head bones. ( applyRootMotion is off.) It seemingly worked fine, but once I strayed from centered animation, I found it gave these blatantly incorrect coordinates:

115015-z.gif

Am I doing something wrong?

I fixed it. My root bone wasn’t taken into account by the humanoid rig. I got what I wanted by interpolating between my characters’ feet instead, then interpolating from that. Less precise, but the job is being done.