The command works great if your esx host is up and has the links defined in the vDS. The issus only presents itself when you rebuild a host. The switch hangs on to the old configuration.
I have 2 physical links vmnic0 and vmnic2. When configured correctly, they are both members of the vDS. When I rebuild the host, you can't start with a vDS uplink. A vanilla install will have a standard switch call vswitch0. it gets vmnic0 by default. Once rebuilt, i have to clear out the host config from the vDS before I can start adding the host back to the switch.
I hope this is making sense. It can be tested by configuring 2 hosts in one vDS (no vSS). log into the console of one host and reset the config to factory and add the server back. Though PowerCLI, you will not be able to add/remove the host/nics from the vDS. The actions work fine in the GUI.
Very strange 