Prefab with Sub-Elements Expansion Button Missing in Project Panel

I have been following along with a course. In this course a GameObject called "Path (0)" is added, this GameObject then has three sub-GameObjects ("Waypoint (0/1/2)"). In the tutorial, the guy drags the parent GameObject "Path (0)" into a folder called Paths in the Project panel to create a prefab. This prefab is shown with a handle to expand it. He then expands this prefab to see the sub-elements which can be dragged into the Inspector, as shown below (expand button highlighted with red box)

When I perform these operations, the Project panel does not have an expand button on the "Path" prefab (see below)

Why does my prefab object in the Project panel not have these expansion buttons?

I can get around this, by using the prefab instance in the Hierarchy panel, but this is a much longer process than being able to access the object from the Project panel.

Any help would be greatly received.