I could not reproduce this issue. Please could include the logs from octavia/0:var/log/octavia ?
$ openstack loadbalancer list
$ juju ssh octavia/0 -- sudo reboot
Connection to 172.20.0.8 closed by remote host. Connection to 172.20.0.8 closed.
<Wait for restart>
$
I could not reproduce this issue. Please could include the logs from octavia/ 0:var/log/ octavia ?
$ openstack loadbalancer list
$ juju ssh octavia/0 -- sudo reboot
Connection to 172.20.0.8 closed by remote host.
Connection to 172.20.0.8 closed.
<Wait for restart>
$ openstack loadbalancer list
$