Windows (ACL) shares - Can't Add built-in users?

[beedix]

I've got a volume that is used by couchpotato for storing media. It's defined as a windows share. Couchpotato runs as the media user. In windows, if I manage the permissions, I can add ANY user\group from the server except for built-in users. If I attempt to add the media user and group, I get an error in windows (see below). Not having the media user\group creates permissions issues for couchpotato as it tries to create folders during the renaming process. Why can't I use built-ins? How could I fix? Temporarily, I've created a duplicate group called "windows_media" which has the media member in it. That works.

But why no built-in users?

 

[dlavigne]

Were you able to resolve this?

 

[beedix]

I guess, but not really.

As mentioned, I created a new media group and added the built in media group to it and that worked....all members of the parent group can create files/folders.

I still don’t understand why the built in media group can’t be used as is. I was hoping to understand why