Build Menu Won’t Open

Hello I’m new to the game. I trying to play the game on my legion go and let steam overlay to map the buttons. All of them work except the build menu won’t open up. I have tried reconfiguring the buttons, verifying file integrity, and a fresh reinstall. I even open up the virtual keyboard to try and press the b button and it won’t work. I also tried using a keyboard and the B button still did not work! Please help!