I agree, the room in the 190 cockpit is very limited in terms of vertical height, but I can't help thinking that as the pilots head moved around.....like they do, it was possible that at certain times the 'bar' could have just slightly obstructed the bottom portion of the sight aperture, and this would have been more apparent when the viewpoint was highest....like when the pilot was at a stretch to look over the nose for that deflection shot.