So I don't know what's happening here - when I move my head with the camera feed, the head will move, but it will stick to the neck/body? Even if the head origin point is in the middle of the head artwork it still does this. When I check for problems there is none... Neither the head or body are independent - if the head is it acts as a independent part would.
If you turn on the yellow mesh of triangles (bottom left corner icon in rigging panel), when you move around you may find a spot becomes clear that is 'stuck' (not moving). Then look for origins and handles at that point. It is typically a tag in the wrong spot or on a handle instead of a layer. Sharing a screenshot of the rigging hierarchy for that area would help track it further
I did what you asked and it seemed that the origin point of the entire artwork was on the neck (for some reason). I just positioned it on the torso and it fixed it!