Small report, this seems to be an issue with activity.php and how it's polling for forum data with the addon active.
template_render_output hook is causing the Forum Name text, and the forum ID to not render on activity.php. It's completely stripped out, everything else is displayed.
Adding in
Code:
AND !in_array(THIS_SCRIPT, array('activity', 'usercp')
at the end of the first if (line 3) of Quick Reply/Edit appears to have resolved the issue - as weird as it seems.
Script effectively becomes this...
Code:
($vbulletin->options['markfl_pbsu_active'] AND ($vbulletin->options['markfl_pbsu_usergroups'] OR $vbulletin->options['markfl_pbsu_users']) AND in_array(THIS_SCRIPT, array('editpost', 'newreply')) AND array_intersect(explode(',', $foruminfo['parentlist']), explode(',', $vbulletin->options['markfl_pbsu_forums'])) AND in_array($this->template, array('postbit', 'postbit_legacy')) AND !in_array(THIS_SCRIPT, array('activity', 'usercp'))