So far as I've been able to determine, group ACLs appear to have no effect at all in macOS 10.13.3.
Given a group "editors" with members "joe" and "jane" who belong to no other groups, and a folder "Revisions" with the following permissions…
drwxr-x---+ 38 mary reviewers 1292 Jan 26 13:37 Revisions
0: group:editors inherited allow list, add_file, search, delete, add_subdirectory, delete_child, readattr, writeattr, readextattr, writeextattr, readsecurity, writesecurity, chown, file_inherit, directory_inherit
…neither "joe" nor "jane" can access the folder.
It appears, though, that user ACLs work. The following ACL, for example, does allow "joe" access:
drwxr-x---+ 38 mary reviewers 1292 Jan 26 13:37 Revisions
0: user:joe inherited allow list, add_file, search, delete, add_subdirectory, delete_child, readattr, writeattr, readextattr, writeextattr, readsecurity, writesecurity, chown, file_inherit, directory_inherit
This appears to be true for both local and open directory users, on both local storage, AFP, and SMB shares.
It's such a massive, obvious flaw that I have trouble believing I'm not missing something obvious. Suggestions would be much appreciated.
(IFS=/; set -f -- $PWD; for arg; do path="${path%/}/$arg"; paths+=("$path"); done; ls -dlae "${paths[@]}")and post the result here. The output shows all ACLs (and POSIX permissions) of the path to "Revisions".