This has happened a couple of times and it’s not a big deal, but a couple of times the lower right node disappeared in the lightning rounds after I fought a match there. It reappeared if I went back to the event menu and reloaded, but I thought it was odd. Again, not a major issue, just a weird bug.
Happened to me too, but only on my mobile (Nexus 4). The Steam version hasn’t given me a single bug of this type so far.
Happened to me on an Ipad last night. I just closed the app and reloaded it and the node appeared again.
In the past, this behavior would occur when you had problems connecting to the game server and the game couldn’t retrieve info to load a new node. This is the first I’ve heard of it happening in recent versions.