After assigning management rights, BES Clients will need to evaluate the assignment and report back that the user is managed prior to computer showing up for the new console operator. So, one possibility is that some of the computers are currently offline and haven’t reported in since the user was assigned to manage them.
I’m seeing the same thing. Everyone has the same access, however most people see 50 workstations, one sees 10 and another only sees 5. 45 workstions are currently reporting in.