If you setup a new site from a database dump it's important that you reset the local state of Content Sync on that site. Otherwise your new site will be mistaken for your previous site which can have many unwanted consequences.
To reset your local Content Sync state:
- Manually edit the "CMS Content Sync" user and set a new password that consists of 60 random alphanumerical characters.
- Run this drush command in your CLI: drush ev '$state = Drupal::state(); $state->delete("cms_content_sync.base_url"); $state->delete("cms_content_sync.site_id"); $state->delete("cms_content_sync.site_uuid");'.
- Open the Settings tab of Content Sync and enter the new base URL.
- Register your site again at the Site tab of Content Sync.
- Open the Pools tab of Content Sync and for every Pool, use "Reset status entities".