When using NT4 PDC with Samba, and trying to add groups to file and directory ACLs from a PC to the Samba share it fails (Samba on IBM AIX 5.1 configured "with-acl"). Adding users works fine but not groups.
From examining level 10 debug output I belive the bug is that the SID is not checked agains GID only UID. Had the check been done to lookup the GID I think it would work, but this is not done. The GID that is used is 0.
