I had the issue of being able to actually start the game when Tacoma released as I tried to get past the "Press 'A" screen. Here are some ways to get around it until it is fixed:
1) Simply do a hard reboot of the system by holding in the power button until the Xbox shuts off.
2) Or, try logging out and starting the game. Hopefully after you hit "A" it will ask you to log in under your gamer tag.
Hope this helps and please go to my YouTube Channel to subscribe!