Tested on the latest nightly (5.0-2877) and a clean Dolphin Emulator folder.
For some reason, Mario Kart Wii cheats simply don't work on the latest nightly. They work perfectly fine on the 5.0 stable, so that's a bit odd. The cheats checkbox is checked and GameCube cheats appear to work fine.
For some reason, Mario Kart Wii cheats simply don't work on the latest nightly. They work perfectly fine on the 5.0 stable, so that's a bit odd. The cheats checkbox is checked and GameCube cheats appear to work fine.