Unable to generate Zoho Service Communication Key (ZSC)

Unable to generate Zoho Service Communication Key (ZSC)

I'm trying to sync Campaigns with CRM, but when I go to Setup > Developer Space > Zoho Service Communication (ZSC) Key, the pane is blank:

I've tried to open this in Chrome, Firefox and IE(with and without compatibility view). I read the help documents on how to populate, and my account is the Administrator Profile, but I don't see any other requirements, so it seems that it should work. Any ideas?