This happens with both formats, Game Sharks and Game Genies. You can't use more than just one code at a time.
If you choose multiple codes it will apply the last one selected. If you return to the cheat menu and select another one, when back to the emulation and after some seconds, that'll be enabled and the others, even saying ON, will be disabled when playing.
Confirmed this is a Core issue, not happening with any other cores (Genesis Plus GX/mGBA/FCEUMMX).
This happens with both formats, Game Sharks and Game Genies. You can't use more than just one code at a time.
If you choose multiple codes it will apply the last one selected. If you return to the cheat menu and select another one, when back to the emulation and after some seconds, that'll be enabled and the others, even saying ON, will be disabled when playing.
Confirmed this is a Core issue, not happening with any other cores (Genesis Plus GX/mGBA/FCEUMMX).