Try :
_Remove all Memcard files from Dolphin 3.5 .
_Play a GC game to create new memcard files
_Dolphin 3.5 - Tools - Memcard manager - Select "Memory Card A" as the old memcard , select "Memory Card B" as new memcard that you just created .
_ Copy "Memory Card A" 's save data to B
If your game is USA version (NTSC) , do not copy your data to EUR memcard (PAL) -> Dolphin can't recognize the save data
_Remove all Memcard files from Dolphin 3.5 .
_Play a GC game to create new memcard files
_Dolphin 3.5 - Tools - Memcard manager - Select "Memory Card A" as the old memcard , select "Memory Card B" as new memcard that you just created .
_ Copy "Memory Card A" 's save data to B
If your game is USA version (NTSC) , do not copy your data to EUR memcard (PAL) -> Dolphin can't recognize the save data
Laptop: (Show Spoiler)
Mini PC :: (Show Spoiler)
