I’ve just had the same problem. Couldn’t get a template to show in the list, no matter what I did.
I ended up modifying line 443 of demomentsomtres-tools.php from
$temp = $mcSession->call('templates/list');
to
$temp = $mcSession->call('templates/list', array('filters' => array('include_drag_and_drop' => true)));
to include the drag-and-drop style templates. For some reason, Mailchimp doesn’t return those types of templates in [user] (which I don’t understand).
Either way, it returns the list of templates now. Hope this helps.
Cheers.