Can't Load URL: The domain of this URL isn't included in the app's domains. To be able to load this URL, add all domains and subdomains of your app to the App Domains field in your app settings.
The 'Click here to verify the API Connection Settings' = 'The settings are correct - do not forget to save your changes!'
I have included any imaginable combination of the website url without any progress or success.
Googling didn't bring an end to my misery.
Any suggestions would be appreciated.