I got a weird issue. We are working on Sharepoint ugpgrade. Hence we have an old SP2010 farm and a new SP2013 farm. We decide not to migrate the User Profile DB. We setup sync connection at both farm to the same AD. The AD's domain name is company.com. Users login with company/user01 to old farm.
After we setup user profile sync on SP2013. It seems fine. All users can login to their site on new farm using company/user01. When they click on "my settings" they can see their account name is company/user01.
However, in the SP2013 CA -> Manage Profile Service: User Profile Service Application page -> Manage user profile. When I search "company" there is no return. It is because all users become "AD/user01", we don't have a domin named "AD"
What can cause the problem? I have tried perform a full sync again but still the same.