So, here's the deal:

As part of my player's preferences, I need to keep track of two different .pngs that represent their first and last name in Chinese. So, when they confirm what their name is, I gather the texture 2Ds and send them to a function in my IO script, like so:

       playerDataScript.lastNameTexture = lastNameChosen.renderer.material.mainTexture;
       playerDataScript.firstNameTexture = firstNameChosen.renderer.material.mainTexture;
       playerIOScript.storeChineseName(playerDataScript.firstNameTexture, playerDataScript.lastNameTexture);

And they're sent to my IO script, where they are handled by the following function:

function storeChineseName(firstName : Texture2D, lastName : Texture2D)
{
    var myFirstName = firstName;
    var myLastName = lastName;
    var filePath = Application.persistentDataPath;
    // Encode texture into PNG
    EditorUtility.CompressTexture(myFirstName, TextureFormat.ARGB32);
    EditorUtility.CompressTexture(myLastName, TextureFormat.ARGB32);
    var bytes = myFirstName.EncodeToPNG();
    var bytes2 = myLastName.EncodeToPNG();
    // Write to a file.
    File.WriteAllBytes(filePath + "/firstName.png", bytes);
    File.WriteAllBytes(filePath + "/lastName.png", bytes2);
}

Unity's told me that I need to encode them to ARGB32. So I've done that with compressTexture. But when I open the .png file unity has made from within the editor, I get errors--and they are completely blank when I open them in Explorer. They are the same size as the original pictures (64 px by 64 px) and they have the correct names, but it's not working, obviously. What am I doing wrong?