Some accounts/security roles can just see specific policies. For example, the maintenance window that is created for their own location and not the others.
When they cloned their own policy, they can't see that until the administrator grant them the "read" permission to the cloned policy.
Release : 8.x
The "read" permission is just granted on specific policies so the cloned policy will consider as a new policy which they don't have read privilege on it.