I'm trying to add users to the system by using build > users and browsing the AD structure for a specific user. I can see all the groups in the domain, but I when I click on the group I can't see any users contained in that group. It's empty!

I know there are definitely users in this group, since I can query it in Powershell and see the users. Upon clicking on the other groups I can find some users, but they appear to be functional user accounts as opposed to real live users that sit at a desk. Anyone know why I can't see users in these groups?
Thanks