Just updated to 18.04.1 I use Terminal only. When I do an su to one my users that runs a game, I only get a $ and no name of the user and does not show current location. Also, tab autocomplete will not work for those users either. I can still navigate just fine if I manually type everything. Tab auto complete works for my regular user as well as root.
getent passwd username | cut -f7 -d:
if you get an empty result it means your user does not have a default shell thus it is using
/bin/sh by default. And that is why it looks like what you are describing.
sudo chsh -s /bin/bash username
to fix the issue