dovecot flags lost after move/copy

Dear Community,

I have a issue with our dovecot server ( 2.3.4.1 (f79e8e7e4) ) with maildir

Flags are lost after a copy (or move), as you can see on this exemple :

• Before doing anything, list detail of a mail : doveadm fetch -u XXX flags mailbox-guid f303160f6df58c5b67040200bc34b0e6 uid 46126 flags: \Seen $Labelimportant

File name also contents the 'e' at the end :

1628631415.M671664P17659.mail7,S=14835,W=15111:2,Se

• Copy it for testing

doveadm copy -u XXX Archive mailbox INBOX mailbox-guid f303160f6df58c5b67040200bc34b0e6 uid 46126

• Fetch flag of this new mail

doveadm -v fetch -u XXX flags mailbox Archive flags: \Seen

File name also don't content the flags -rw------- 2 XXX users 14835 août 10 23:36 '1628631415.M671664P17659.mail7,S=14835,W=15111:2,S'

Do you known how to keep flags after move and/or copy ?

Thanks in advance

Chris