Cannot Grant Extended Permissions

I am able to use this app on several of my WPMU blogs but it's not working on one of them. I am able to get the greenlight on the API credentials. The problem is with granting extended permissions.

I am unable to grant extended permissions. There are no error messages.

I created a new app just to see if that was the problem but it's not. Same problem.

I have turned off all other extensions to see if that is the problem at it still does not grant extended permissions.

I have also deactivated and deleted the plugin and downloaded the latest version and then uploaded and reactivated and it still does not work. What else can I do???

I have also logged out and back in to Facebook and WPMU to no avail.

I have also cleared my cookies and browsing history and rebooted to no avail.