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); } }