Mailbox migration stalled

We're migrating mailboxes from ex2010 to ex2016 onprem.

Almost all the migration went fine but at the moment we have one that always stall with the error

StalledDueToSource_MailboxLock

We already tried to

- stop/restart

- delete the move request and recreate it

- restart replication services on source and target servers.

the migration always stall.

how can we fix it ?

thanks