Hi @sapimsa ,
Should be able to migrate VMs online within a cluster, unless the destination does not meet certain requirements or if there are other limitations.
1. You had mentioned that you had to power off vCSA to migrate to another host. What was the error reported when you tried to migrate vCSA online ? Please share screenshot, if possible.
2. Post vCSA reboot, please check the status of update manager service and if required perform a restart
service-control --status vmware-updatemgr
service-control --stop vmware-updatemgr
service-control --start vmware-updatemgr
Hope that helps