Volume backups go first, and one that can't start says so

A volume backup's copy off its server goes ahead of Runtime's own copies there, never behind one, and copyStartedAt says when it began. A backup whose copy hasn't begun 15 minutes after you asked fails with errorCode backup_stalled rather than staying pending, unless other backups on its server are moving up the line. The volume is unchanged; back it up again. See volume backups.