child theme files no longer displaying in theme editor

Hi there,

Not sure if I understand.

That's exactly what a default child theme should look like.

Let me know what I'm missing :)

My understanding is that i installed the independent child theme so that I can customize the header.php code without updates effecting the file. how do i access the independent header.php

You would copy the header.php file from the parent theme and add it to your child theme folder:
https://github.com/tomusborne/generatepress/blob/master/header.php

Then make changes to that file.