Known problem:
https://www.petrockblock.com/forums/topic/mupen64plus-ricrpi-branch/page/2/#post-83366

Thanks for your support I just went through the retropie_setup and installed n64 with retroarch and now the esc button works! But now the keyboard up/down/left/right key do not work. It’s also not in fullscreen even though in config file fullscreen is set true. Not a big deal tho.