Comment 3 for bug 1569064

Can you attach your /etc/default/lxd-bridge and "sudo systemctl status lxd-bridge"?

Just confirming that everything looks sane on that front.

It does look like systemd triggers on the interface and expects ifupdown to configure it, waiting forever for it to do so, despite the possibility that the interface isn't ifupdown-managed at all and that there is therefore no way for ifupdown to do anything about it.