DataManager Thread_FirstPost help.

[Blindspot]

I have the following code which worked perfectly in 3.8.x...

PHP Code:

$threaddm =& datamanager_init('Thread_FirstPost', $vbulletin, ERRTYPE_ARRAY, 'threadpost');
$threaddm->set_info('forum', $foruminfo);
$threaddm->registry->options['floodchecktime'] = 0;  
$threaddm->set('forumid', $forumid);
$threaddm->set('username', $username);
$threaddm->set('title', $title);
$threaddm->set('prefixid', strtolower($section));
$threaddm->set('pagetext', '$placeholder');
$threaddm->set('allowsmilie', 0);
$threaddm->set('lastposter', $username);
$threaddm->set('visible', 1);
$threaddm->set('dateline', time());
$threaddm->pre_save();
...
$threaddm->save(); 


in 4.0.x it creates a thread as expected, database info looks fine... however...

When I view forumdisplay the prefixid's don't show. Am I missing something?

If I advance edit the thread and assign the prefixid again it does show.