Session-based Multiplayer and GameInstance help

I’m trying to make a multiplayer game using the session nodes and I have failed to make anything work.

When I host a game using a listen server, the clients all get black screens. This may be because of another problem I’ve posted here.
When I host a game using a dedicated server, the game crashes.

There’s very little documentation on these nodes and I’m having trouble wrapping my head around how and where to use them. I’ve been using the Multiplayer Shootout as a template, but it’s not being very helpful since I’m getting the same results when I run that.
However, when I try to host a game using a listen server on THAT, an error message flashes saying “Error: connection to host lost”.

Any help to my problem or insight into the workings of multiplayer sessions would be greatly appreciated.