After using the esxcfg-vswitch command, it appears on the command line that the port group was successfully created.
# esxcfg-vswitch --add-pg=PG01 vSwitch0
# esxcfg-vswitch -l
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch0 3920 7 128 1500 vmnic0,vmnic1
PortGroup Name VLAN ID Used Ports Uplinks
PG01 0 0 vmnic0,vmnic1
...
But you can't see port groups in Host Client or vSphere Client.
To create portgroup via CLI, use esxcli command instead of esxcfg-vswitch command.
See "A standard portgroup can be created on a Standard vSwitch with this command:" in Configuring Standard vSwitch (vSS) or virtual Distributed Switch (vDS) from the command line in ESXi