I used our Autotune logs to check the site that you are working on. On the forum page, the following Javascript error is thrown when I try to login with Facebook:
Uncaught TypeError: jfbcJQuery(...).modal is not a function
The problem is that your home page is loading the normal version of the Bootstrap Javascript library. Your forum is loading a different version of Bootstrap from:
/plugins/system/pagebuilder/assets/3rd-party/bootstrap3/js/bootstrap.min.js
That version doesn't look compatible with what JFBConnect expects.
There's two options to fix this:
* Set the "Include jQuery / Bootstrap" setting in JFBConnect to "Yes". This will ensure the proper version of Bootstrap and jQuery are included on every page.
* Disable the "Show 'Logging in' Popup" in the Facebook configuration area. This will prevent the "You are now being logged in using Facebook" message, which requires Bootstrap to show
I hope that helps get you going,
Alex