Welcome to the WPML support forum. I will do my best to help you to resolve the issue.
May you were not able to upgrade because of the staging site. So the site key for the automatic upgrade will be showing a mismatch due to a different URL.
Please try the following steps to register the site with a new key after a full site backup{mandatory} and make sure you are getting the expected results or not.
- Go to Plugins>>Add New>>Commercial tab
- Click on *Register WPML* link
- Click on "Get a key for this site"(New we can generate site key for Development sites also)
- Copy the newly generated code
- Visit back to Plugins>>Add New>>Commercial tab
- Register the site with the new key
Please refer to the following documentation for more details.