Interface members source list is empty for new Software Switch interface - FortiWiFi 50E

Using GUI, I am setting up a second software switch interface, but discovered when adding to the "interface members" that the source list shown to the right has nothing in the list.  I expected to see "lan" and "wifi" so I can add those as interface members.  Research indicates this has been a problem with others, and it was recommended that the following CLI commands would fix the problem:

conf sys int

  edit port1

    set description "LAN"

    set alias "LAN"

  next

end

However, when I enter "next" I get the following:  Attribute 'vdom' must be set. Command fail. Return code 1.

I am not using virtual domains, so am at a total loss of where to go from here.

Any help would be greatly appreciated.

Thanks!

DonD