Lalauri89 The saves are supposed to be in Documents > Electronic Arts, and that doesn't cause any problems other than the OneDrive-related info you've already found. I was saying that if the program files are also in Documents, the EA App might empty the folder when updating because it's checking the contents of the folder that contains the program files for anything out of place. So if your game is installed elsewhere, this isn't why your saves disappeard.
Other than that, and OneDrive, and possibly a virus, I don't know how the data would have vanished. But then there are plenty of similar reports where I can't pinpoint a cause.