The backing helper disappears

In a fictional training exercise, a driver plans a slow backing maneuver with a helper. They agree on signals and a position where the driver can see the helper. During movement, the helper unexpectedly disappears from view behind an obstruction. The driver cannot confirm whether the helper moved clear or entered the path, and a mirror also leaves part of the area unseen. A learner proposes continuing slowly because no collision has occurred yet. Another says the missing information should be resolved before movement continues. The task supplies no automatic proximity system or indication proving the path remains empty. It asks for a decision based on the known visibility and communication limit, together with why an earlier walk-around cannot guarantee an unchanged scene.