You've set up Hybrid Connect with a Facebook app on your site and everything's working fine. Then suddenly, it stops working!
What the heck is going on here?
Facebook Apps and DomainsMost commonly, this happens when you install Hybrid Connect on more than one domain/website and you use the same Facebook app keys for the plugin on several sites.
Facebook apps are domain specific. If you enter the keys into Hybrid Connect for one domain, it will automatically set the app to work on that domain. When you enter the same keys on a different site and different domain, Hybrid Connect will again automatically set your app to work on that specific domain, which means it will no longer work on the previous site.
The solution is simple: you need to create a separate Facebook app for each domain you want to use Hybrid Connect on.
This is a requirement by Facebook, so there's unfortunately nothing we can do to change it. It's very easy to set up apps, though, so it's not an issue that takes a lot of time to fix.
For instructions on how to set up your Facebook application, see this page.