I have a custom field in which I have selected Yes for Visible on Profile but have set the Visibility field to an ACL group which the user is not a member of. I thought that this would mean that administrative staff in the ACL would see the field in the user's profile, but not the user, allowing us to have a "Private" administrator only comments field which the admins could easily view via the user list feature and clicking on a user to see the profile entries.
However, when I log in as the user, that field is visible on their profile even though they are NOT a member of that ACL group.
Am I misunderstanding the way this feature is supposed to work, or is there a bug?