I just downloaded the Orion Beta 4.0.0+52173. After building the CallbackSample, the event callbacks for image, hand position, etc. work, but the callback for OnHeadPose is never called. The only comment on LEAP_HEAD_POSE_EVENT mentions needing to enable positional tracking. I haven't found a way to do that.
Am I just missing how to get this event to happen? Is there a setting somewhere? Is the feature not actually implemented?