Ultimate FB 1.0.9
Network install, all sub sites using the master API key / IDs / etc
Domain Mapping Plugin
I can't remember if this is the first time I've tried to Grant Extended Permissions on a domain mapped site, but when I do I get this error in the FB pop-up that usually has the Allow button:
API Error Code: 191
API Error Description: The specified URL is not owned by the application
Error Message: redirect_uri is not owned by the application.