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:
uuid: 236fa77c-d83e-42de-8a03-03c574c00160
name: Drupal 8
mail: [email protected]
slogan: ''
page:
403: ''
404: ''
front: node
admin_compact_mode: false
weight_select_max: 100
langcode: en
The config import has a different UUID, you can confirm the UUID with the following command
cat sites/default/config/staging/system.site.yml
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.
cat sites/default/config/staging/system.site.yml
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.
source: http://enzolutions.com/articles/2014/08/27/understanding-configuration-management-in-drupal-8/