When you enable FSLogix for a new host while running the wizard, no additional steps are necessary. On wizard completion, the host is rebooted and is added to the active load balancing. An existing host must be rebooted manually using the Tasks > Tools > Reboot menu option.
To reboot an existing host with Parallels RAS Management Portal:
Go to Infrastructure.
Select the RD Session Host that you need.
Go to Overview > expand Control > Reboot.