grant extended permissions

Similar to post https://premium.wpmudev.org/forums/topic/i-cant-get-past-the-facebook-api-tab-even-though-i-made-a-facebook-app – I am having the same problem. Set up a facebook app okay, put all the credentials into the plugin, and when I click on “grant extended permissions” – nothing happens. I have tried this on 2 sites on the same server with the same result. Any ideas?