In 5pm Clients are a separate type of users that are assigned directly to the Projects and can see just those projects.
Projects can also be grouped into Groups (can be used to split project by departments, types, etc.). Many of our user though use Groups to split Projects by clients (one Group for each Client). Naturally, Clients will not see any projects in other groups that are created for other clients (since there are no projects there assigned to them), but they will still see the names of the Groups. This could be a problem, since the names can be suggestive and reveal information about other Clients.
Since it makes no sense to show the Clients the names of the Groups in which they don’t have any projects, we decided to change this behavior and from now on to hide those unrelated Groups from Clients.