While setting up User Profile service application (UPS or UPA depending on religion) i saw some weird behaviour that broke my sync in Forefront Identity Manager (FIM). Somehow I ended up with two user profile properties that was mapped to the same AD property:
I remembered that in MOSS, when you mapped a profile the property dissapeared from the list of available properties to map from AD:
I found out i had this problem when new users created in AD didnt show up in User Profiles. As Spence warns in his post on configuring User Profile
you will receive no warnings in SharePoint logs when sync goes awry, so i fired up FIM service manager (C:\Program Files\Microsoft Office Servers\14.0\Synchronization Service\UIShell\miisclient.exe) and found out i had "completed-sync-errors". Checking into that i found 10 unexpected-error's for data source attribute Title.
I also tried creating new properties, and had no problem matching several user profile properties to the same AD property:
While I cannot tell you if this weird behaviour is per design or not, I can tell you that this has changed since MOSS and that it breaks FIM sync and can be hard to catch! Hope this helps out others that are wondering why their user profiles suddently stop getting added :-)