This problem was already reported years ago in this post #1641 opened by @fzurita. The suggestion was to enable the "Copy auxiliary buffer from RDRAM" option, which works but causes a significant performance hit (i'm on Android with an SD 865 and M64Plus FZ Emulator).
In the same post @oddMLan and @gonetz speak about a hack that fixes the problem. May I know what that hack is?
Thanks.