Comment 2 for bug 1719889

Hi,
it seems there were similar issues discussed in bug 1307778
They got resolved groupds with no GID in AD, but still ended up having the issue around S-1-18-1 that you reported.

Looking back how the other issue was fixed I really think you should try to recreate the issue on the latest version in Ubunutu (e.g. 4.7.6+dfsg~ubuntu-0ubuntu2 in Ubuntu Cosmic or even newer but not yet released 4.8.2 from https://launchpad.net/~ahasenack/+archive/ubuntu/samba-merge-4.8-1778125).

This most unlikely is a bug in Ubuntu, but in the upstream code.
Therefore if reproducible there report it upstream in https://bugzilla.samba.org/enter_bug.cgi and report back here the bug id so we can track and include the fix.