Currently there is a bug that occurs with role select when you change from (for examples sake) DPS to Healer by unticking the box for DPS and ticking the Healer box.
If you do this and someone accepts their role it will revert your choices back to what it was.
This can cause problems if you get an insta-pop as the player is then locked into the spec that the game reverted back to on your role-check.
Minor issue but still annoying nonetheless for people who like to play multiple roles. Most times the queue can be cancelled in time and the issue can be rectified but in the case of an insta-pop you are stuck.
Quick solution is just to be the last to choose your role but if there are others with the same problem, chances are 1 person might screw this up.