I still need to PR some changes to atmosphere and libnx, so for now you have to use this mupen64plus-next build to make use of the patches:
https://m4xw.net/nextcloud/index.php/s/n87e8ycGGgfTM6L
Also you have to use this method for best compatibility: https://gbatemp.net/threads/use-atmosphere-to-access-full-ram-with-homebrews-without-nsp.521240/
Note: You don't need this hekate version if you are on fw 4.0-4.1.
If you are lower than 4.0, this won't help you!
Make sure to start your CFW via hekate, don't chainload fusee (yes people did that before with this build, patches won't apply then).