This bug has been here for a while and still has not been fixed with the anniversary update.
When you are switching/selecting characters during the countdown before a game starts, and you press the View button (Double rectangle on Xbox Controller above D-pad) to see the Daily and Weekly Challenges, theydo not respond to the XBOX shoulder buttons on the controller to switch between them and see.
This issue does not exist when in Quick Match Main Menu or when viewing the challenges in the event pass.