[kh99]

In file showgroups.php around line 117 is this:

LEFT JOIN " . TABLE_PREFIX . "usergroup AS usergroup ON(usergroup.usergroupid = user.usergroupid OR FIND_IN_SET(usergroup.usergroupid, user.membergroupids))

if you remove the FIND_IN_SET part like this:

LEFT JOIN " . TABLE_PREFIX . "usergroup AS usergroup ON(usergroup.usergroupid = user.usergroupid)

then I think it should do what you want. That information is cached, so you either need to clear the system cache or else wait until it refreshes (I think the default cache time is 3 hours).