Save data not writing, gamecube

[LPFaint99]

did you change the memory card filename or is it still the default?

I believe the saves on mac are stored in "Library/Application Support/Dolphin/GC/", but I could be wrong.

These errors usually write permission related verify that you have rw permissions on this folder.

you can always try the standard os x application troubleshooting of repairing disk permissions (from disk utility) and testing in a *new* user account