Can't see some of our AD users

We connected our XWiki to our Active Directory so that our users can login with LDAP authentication. Problem is that not all users are listed in XWiki, a lot of them are missing. The missing users seem to be unable to login with their Active Directory password, unlike the users listed in XWiki. I don’t remember adding any specific AD user to XWiki, they have been able to login since we set up LDAP authentication. Do you have any suggestions?

Nobody had this problem before?