I can't get a Luigi's Mansion backup to work. Every time I press start at the title screen, it freezes. I checked the compatibility list and it says it works, but for me it doesn't. I have no idea what's going on!
Which MIOS are you using? WiiGator's? The list notes "edit: I had to use option B from the launcher. Hangs loading from disc channel."
It's been a long time since I disc loaded backup gamecube games, but I remember there being a WiiGator screen that came up allowing you to choose different load options for the game. Pressing B for patched MIOS was required for certain titles, and it looks like it's required here.