Unable to assign different NSG LAN ports to different Port Groups

gsg

I am trying to assign multiple switches, connected to different LAN ports, to the same network (f.e., NSG is 10.0.0.1, Switch1 on P3 is 10.0.0.2, and Switch2 on P4 is 10.0.0.3).  I was informed by a support rep that I can do this by using PortGroups, and was shown a screen clip with multiple Port Group configurations on the 'Security Gateway > Interface Addressing' page, but I can't get my Nebula Sites to create/show different Port Groups, it only shows, under the "Port Group Setting" header, "LAN1-6".  Even if I configure another LAN Port with a different network subnet, it doesn't change.  The only way I can get it to change is by configuring a LAG, after which it shows "LAGx" under the "Port Group Setting" header, but that is not what I want to configure.

The Zyxel Support rep stopped replying to my ticket after he requested, and I sent him, a screenshot of my setup.  I don't know what happened, maybe he got a new job.

Hoping someone here has seen this issue and solved it, and can give me some direction.

Thanks in advance!