Please follow the steps below to resolve the issue:
1. Go to your WPML account (https://wpml.org/account/sites/) and delete the existing site key for the affected site.
2. In your WordPress admin, go to Plugins → Add New → Commercial tab, and click Unregister WPML from this site.
3. Once the page reloads, click Register WPML. When prompted, click Get a key for this site.
4. In your WPML account, complete the site key setup and make sure to set it as a Production site.
5. Copy the newly generated key and paste it into the Commercial tab on your site.
6. Update the plugins.