Why after making a Prefab out of gameobjects in a new project the prefab objects are empty ?

In the first project i can see under dron012 all the objects.
I can select them and see them in the scene view:

Then i did in the menu: Assets > Create > Prefab
Then i dragged into the new Prefab the drone012

And if i will drag now the new prefab to the hierarchy it will work fine on this project.

Then in the hard disk in the directory of where i created the new prefab i copied the file: Drone.prefab to a directory in my other project i have.

In the other project i see the prefab but when i drag it to the hierarchy and then click on the objects i don’t see them:

I click on Sphere but see nothing in the Scene view.

You can export the asset (prefab) and all his dependencies as a package.
And in your another project just import that package