Installed 4.1.3-1 from CD. Initial reboot fine.
Rebooted - monit not start.
Manually started monit:
Made a load of changes via web gui, including LUKS encrypted volume.
After a reboot, LUKS failed to unlock volume, monit failed to start.
OMV well broken, reinstalled everything except openmediavault 4.1.8-1, so far OK.