User should be a user added on the main site.
Manual registration does not automatically add the user to the main site.
Ultimate Facebook plugin automatically add the user to the main site that’s why those registered via Facebook were the only names being returned.
I have to manually add those “unassociated” users to the main site.
Not all users are being returned.
For example, I’m expecting some users to appear as i type @aa or @ab
Yet, there are some users successfully returned.
Weird behavior.