Not a bug but an improvement. It can be frustrating waiting for a guild to play against... why not have the guild face a random team when they are no people in the guild queue?
Or perhaps you could have it so that the game can start 3 vs 3 or 2vs2 instead of 4 vs 4 like similar to how the random team matches start. If guild matches allowed smaller teams, more guilds including smaller ones could participate!
There won't be guild vs random because guild teams are normally far more organized then a random team, you know exactly how good your team mates are. Random on the other hand is a pug. Pitting them against each other would be extremely unfair for the random team.
Use FSC as an example. A guild team can kill Vana almost every time because you all know your roles and what you're doing. A pug is random, and you have no idea how good the people are, what their equipment is (not an issue in blast network, but it helps with the point), and you have no idea if the team will be able to kill Vana. One is organized, the other is herp derp I hope this works
~Gwen