Unable to write files to storage [SD or Internal] when building with IL2CPP in unity 2018.1.0b4

When I build with IL2CPP in unity 2018.1.0b4 and try to write a file to the storage nothing happens!
here’s my code…

using UnityEngine;
using System.IO;
using Newtonsoft.Json;

public class Serializer : MonoBehaviour
	public void Serialize ()
        string json = JsonConvert.SerializeObject(saveData, Formatting.Indented);

        File.WriteAllText(Path.Combine(Application.persistentDataPath, "savegameData.json"), json);

The same to me man. AND NOBODY HELPS!, there is nothing out there that can help us. I have done all that they say and it never Works. I have almost the same code.
I had tried with persistentDataPath, Environment.Personal, dataPath with the same behaviour: EDITOR WORKS AND THE BUILD NOT.

Good work UNITY, I have never seen such error like this, NEVER!.