Gizmos.DrawWireSphere not working

I am trying to follow a tutorial by brackys (ENEMY AI - Making an RPG in Unity (E10) - YouTube) to make an AI follow controller. When I tried to use the script in the tutorial on a prefab; I did not see the sphere on the prefab in the scene editor. I tried it again by following the tutorial step by step and I still cannot see the sphere on the cube shown in the tutorial.

Is it the Unity Version I have (2019.2.14f1)? Is there a different script to get this sphere now?

Thank you for the help!

Have you enabled the Gizmos button?