When you use the Radial Menu for gamepad in Gamemaster, you control which function is highlighted with your right-stick, but it's not stated on the screen that to select your function you press the right-trigger on your gamepad. I think this is the only time that right-trigger is used in this way, so this will cause confusion to gamepad players.
I've tested this on Xbox & PC Game Master Mode.
It's probably best just to add an on-screen tool-tip that says "press RT to select" rather than change the stick function to the left stick and change the select function to X or A buttons.
Thanks, Rob.
Here's a video showing it in action: https://youtu.be/Kry6NwxdiHY