In the urbackup management interface, I mounted the image file, but there was no display?

My version is 2.2.7+centos7+nginx+Btrfs. In the management interface, I have mounted the backup image file, but there is no display. There is no record of any errors in the log.

@uroni @orogor

Try stopping the urbackupsrv service and running it manually in debug mode and then try to mount the volume. You should see mount errors in the debug output.