dsync backuping folders only, not emails

Hi guys,

I have an issue when I try to backup a remote mailbox, apparently it exits with no errors, it creates the mailbox folders in local, but it doesn't copy any email.

doveadm -Dv -o dsync_features=empty-header-workaround -o imapc_host=secure.emailsrvr.com -o imapc_password='passwd' backup -R -u somemail@counselorinberlin.de imapc:

Any hints?

All the best, Istvan