markAsSeen() not work

[xfdr0805]

php version 7.2
imap 1.8
ubuntu server 18.04
IMAP c-Client Version 2007f

Q1:
//$message->markAsSeen(); not work
//$mailbox->setFlag('\Seen','21'); not work
$message->setFlag('\Seen \Flagged \Deleted \Answered');
\Seen or \Unseen is not marked [unseen] field
output header:
[recent] => R
[unseen] =>
[flagged] => F
[answered] => A
[deleted] => D
[draft] =>
[msgno] => 20
Q2:
$messages = $mailbox->getMessages((new Unseen()), \SORTDATE,true);
always return all emails

$messages = $mailbox->getMessages((new RawExpression('SUBJECT "[结案通知]样品联络单" SINCE '.date('d-M-Y'))), \SORTDATE,true);

This works fine, but it's slow when there's a lot of mail, so if you only receive unread messages at a time, it's good to finish processing the messages marked as read