We have tried to investigate, but weren't able to recreate the issue. Can you tell me if you go into the CB User Manager if the user that was just registered is marked as inactive and unactivated? If so, that can be an indication that there is some field in CB marked as "Required" that isn't being filled in when the user registers. When using JFBConnect you need to make sure that every required CB field has a profile mapping for it *or* you are not using the Automatic registration feature and are letting the user fill out those required fields.
I hope that helps you investigate things a little further on your end, but if not, let us know. The next thing for us to look further would be to ask for Super Admin credentials so we can understand your configuration better.
Also, on a side note, a user responded to another forum post of yours about how you added the social login buttons to CB. I'm not sure if you are interested in responding, but we'd love to know what you ended up doing as well. We'll likely incorporate any feedback you have into our documentation to help other users as well. The specific post is:
www.sourcecoast.com/forums/non-commercia...unity-builder#p42704
Thanks,
Alex