This issue is resolved in Cloud Director 10.1, available at
VMware Downloads.
Workaround:
To workaround the issue power off the affected VM before making changes.
If the VM properties are being edited and it is not desired that it change resource pool use a method to stop vCloud Director from performing a migration such as temporarily disabling resource pools in the Provider VDC, or using affinity rules to keep the VM in place.
Alternatively configure the Provider VDC's backing ESXi clusters to all use the same distributed switch for VXLAN preparation in NSX so that a change of port group is not occurring during the migration.