I logged as root, and moded a user:
usermod -G audio,users,webadmin
Then I used groups to see if the operation was successful.
audio users webadmin
But when I logged as fluke,
I showed audio users, which was the same as that operation.
If you were already logged in as fluke when you ran usermod, did you log out and back in before running groups as fluke?
I ran usermod as root
and then ran aroups fluke (still as root), showed correct qroups of fluke
Then, I logged as fluke, ran groups, I cant see any change, groups still the same as before
gpasswd -a fluke audio
to add a user to a group.
And does the webadmin group exist (in /etc/group) ? If not, create one with groupadd.