Just to confirm, you're using Advanced UM so that there is Sync between inbox and NuPoint, correct?
If so, I believe you can take a look at the ldap/current log.
I've had issues where the email address within AD didn't completely match the user's email address and it therefore couldn't associate the two and sync. They had to match exactly in order for sync to work. (In my case, the email address was <firstname><FirstLetterOfLastName>@ but their AD email alias was only <FirstName>.)