[UPDATE] It seems to work correctly under 10.12. And before I restored the UCS from a backup it worked under 10.13 and 10.14.
It only shows the incorrect groups when logged in and I run the id -Gnr $USER under 10.13 and 10.14 and when I check another user on 10.13 or 10.14 bash command. It works correctly and shows the active directory groups like “Group\DOMAIN”. This is really screwy.
groups username
But if I check
groups myusername
It too returns the weird screwy groups like id -Gnr $USER