However, I think the playlists aren't working as in intended. The first four games I played were all on Array, and I was on the defending team for every one. At this point, I backed out and reentered the playlist for two games, which were both on Summit, and I was was on the attacking team for both of them.

It doesn't seem like the playlist is mixing up maps or attack/defense for me. Obviously a sample size of six is small, but I would think there would be some variety there. How often can you really expect to play the same map on the same side? Four times in a row seems like it's broken.