When selecting the "Restart Now" option in the Management Console (Maintenance > System and Disks > Tasks > Restart Now) the ISG proxy does not restart.
This is a known bug that is currently being investigated. It only affects ISG proxy devices.
Workaround: Restart using the CLI
abrupt Reboot system abruptly, according to restart settings
regular Reboot system according to restart settings
upgrade Reboot system to start running new image