When you map a drive to a 'server' share point, and remotely edit the NTFS permissions, only explicit permissions remain?
The client interprets the mapped drive as the root of a drive, which doesn't have inherited permissions.
This problem is common to all versions of Windows, NT 4.0 and higher.
The only solution is to logon to the 'server' console to edit the permissions.
You can remotely edit permissions below the mapped drive letter.