This is a very popular video game and due to the size of users you can expect some issues (or problems) surfacing. This page is simply to list the common things to look out for and possible fixes until the development team can sufficiently address them.
Session Freeze During Online PlayEdit
Sometimes a player's connection to the Internet or the game will cause lagg for all players. If this happens to you, either wait it out or try to toggle the "Sit Out" option. If the Next Button isn't working then press the big Xbox button in the middle of your controller.
Not a lot of Human Players During Online PlayEdit
This can be a good or bad thing. On the good side, with freezing being an issue, the less human players you have the smoother the sessions will run. On the bad side there's not a lot interacting going on. One solution would be to use the "Prefered Players" option. Using that will help you play with players you've played with in the past without having to put them on your friends list. Xbox 101 covers it.