I have a synced environment and i am unable to hide a user from GAL and unable to do so.
Steps performed till now :
1. I went to ADSI Edit and changed the attribute's msexchhidefromaddresslists property in it.
2. Ran the sync, still didnt change
3. In order to check if the sync is working , added a alias and ran the sync, it worked
4. Thought, it might be some OU ( guessing ), created a new OU , transferred the user there ( made sure that the OU is syncing ) still the value is false.