There seems to be an unintended side effect of the private attachments, as bugnote_add_inc.php still contains the lines:

$t_attach_style = ( $t_default_bugnote_view_status != VS_PUBLIC ) ? 'display: none;' : '';

?>

<tr id="bugnote-attach-files" style="<?php echo $t_attach_style ?>">

As the change of the attach_style was removed, it is not possible to do file uploads, if default_bugnote_view_status is not VS_PUBLIC.

The $t_attach_style is not necessary any longer.

?>

<tr id="bugnote-attach-files">