Network.matches is Null

I'm trying to create a basic lobby using a custom network HUD. Everything works, except that whenever I try to use manager.matches, it is null. My manager is the stock NetworkManager component. I've checked that manager is not null, since I am able to create and join matches. I enabled matchmaker and all that stuff.

I've checked out the stock NetworkManagerHUD class, and it seems that what I'm doing should work. I've added NetworkManagerHUD to my project, and it is successfully able to call...

Network.matches is Null