I am going to piggy back on this thread too. Sorry @MLafflin! I am hoping this is related and providing my details might help. If not I will delete.
I have not been able to get any switches to show up. they show up as IP's and web servers but not really as switches.
For example a Cisco SG300 shows up as such but nothing shows attached to it. I can log into it there are no scanning errors. It has https access, snmp, ssh, etc so I can't understand what is wrong.
A dell x series switch I have does the same, I can log in and manage it but LS cannot for some reason get in and see devices. Is there a walk thru to make this work?