I believe bans can only be levied by Admins and Global Mods, this is intention as mods should only ever have power over the categories they moderate.
Flagging users can be done from the user's profile, under the dropdown:
(Don't worry, I didn't flag you 😄 )
Assignees should also list all users with the Moderate privilege. If it doesn't show them, then it is possibly a bug...