Problem: If you're experiencing an issue where the 'This site is registered on WPML.org as a development site' notice still appears after following the setup instructions, and you cannot add a new plugin via the admin UI, this might be due to WPML detecting a change in the site URL. Solution: We recommend following the steps provided in the migration banner that appears when WPML detects a site URL change. It's important to ensure that if both sites involved share the same site key and one of them was moved or duplicated, and both sites are currently active, each site must have its own unique site key.
If this solution does not apply to your case, or if it seems outdated, please check the related known issues at https://wpml.org/known-issues/, verify the version of the permanent fix, and confirm that you have installed the latest versions of themes and plugins. We highly recommend opening a new support ticket if you need further assistance. You can do so at WPML support forum.
