The Configuration Management only allow sync configuration between same site or project to avoid issues importing configuration from site a.com to b.com, to accomplish this validation Drupal 8 generate a UUID for each site.
You cat get your current site UUID executing the following command:
drush cget system.site
The command above we will have a similar output to next listing:
name: Drupal 8
mail: [email protected]
The config import has a different UUID, you can confirm the UUID with the following command
For that reason you need to change the value of Site UUID using the following Drush command:
drush cedit system.site
The command above enable you to use your favorite text editor to set the same UUID present in staging config files.
After change the UUID and change the permissions, if you visit again the page example.com/admin/config/development/configuration you will see all changes, deletions, renames, and additions.