Success! Thanks for the help.
Solution using the CB Query field posted for others wrestling with displaying the usergroup in profiles and lists. Substitute your database prefix for cms.
Code:
SELECT cms_usergroups.title
FROM (((cms_users
INNER JOIN cms_user_usergroup_map
ON cms_users.id = cms_user_usergroup_map.user_id)
INNER JOIN cms_usergroups
ON cms_user_usergroup_map.group_id = cms_usergroups.id)
INNER JOIN cms_comprofiler
ON cms_users.id = cms_comprofiler.user_id)
WHERE cms_users.id = [cb:userdata field="user_id" user="#displayed" /];
Worked through many permutations before finding a query that worked as expected. Is there a reference for cb substitutions beyond the "Using Substitutions throughout CB". I clearly need to improve my working knowledge of CB.
Thanks again!