It’s called a “squawk code”, because the code is broadcast steadily, it is like a bird squawking.
The code will enter itself when you get ATC clearance.
The radios are in the FCDU, the nav rad pushbutton.
You enter them in from the FCDU keypad.
If you already knew all this and it’s no help, have you tried turning all your assists off and see if you still have the issue.
Hello,
I am sorry to hear of your problem. I have moved your topic into the new Bugs & Issues category that launched today. If you keep it in the old one, it will be closed within a week.