I hate to to say this, but I hit another bug in ns7rc3, I think.
After installation of ns7rc3 from iso with accountprovider nsdc is working:
when I create a shared folder like this:
the folder is created and accessible with user credentials, but in ‘users and groups’ this appears:
and domain accounts look like this:
This is not reversible. When I delete the folder and do a reboot, it remains unjoined.
It smells of this
Is not the same situation but just for information.
I had no issues when I have created shared folders after upgrade from rc2 to rc3, followed the leave and join procedure.
I can see and I can access the new shared folders, from Windows explorer -> Network.
@davidep I think I have to apologise. 
I changed the workgroup prop in smb-db to another value with config setprop smb Workgroup xxx
Now I changed it back to default and the shared folders are working. I can create and access them.
I’ll change the topic from bug to suppoprt and mark it as soved.
It was my own fault. But anyway I can’t get why this happens.
Did you run any event?
Yes: expand-template /etc/samba/smb.conf and systemctl restart smb.service.
