Was trying to import a user into unity from exchange today and can not find him there. His exchange account is there and everyone else on that server/cluster shows up but not this person...I have done this many times and 3 or 4 users today but for whatever reason I can not locate this person. Not sure if this is a unity not being able to see exchange issue or a unity issue or an exchange issue...am a bit confused on this
You may want to clean the user with the Remove Subscriber Properties Tool if you haven't already:
Hope this helps. If so, please rate.