ScriptableObject loses data when I hit Play

I want to use SortedSet for Auto-sorted-list on my ScriptableObject to store data like this:

 [CreateAssetMenu(fileName = "ScoreList", menuName = "ScriptableObject/ScoreList...")]
 public class ScoreList : ScriptableObject
 {
     public SortedSet<Score> scores = new SortedSet<Score>();
 }

My Class Score:

 [System.Serializable]
 public class Score : System.IComparable<Score>
 {
     public float percent;
     public Material material;
     public Sprite sprite;
 
     public int CompareTo(Score other)
     {
         float ret = percent - other.percent;
         if (System.Math.Abs(ret) < 0.001)
             return 0;
         else
             return ret < 0 ? -1 : 1;
     }
 }

Unfortunately Unity don't support SortedSet in Inspector windows so I make a CustomEditor:

 [CustomEditor(typeof(ScoreList))]
 public class ScoreListEditor : Editor
 {
     ScoreList scoreList;
     Score score, delete = null;
     bool IsOpen = false;
 
     private void OnEnable()
     {
         scoreList = target as ScoreList;
         score = new Score();
     }
 
     private void OnDisable()
     {
         EditorUtility.SetDirty(scoreList);
     }
 
     public override void OnInspectorGUI()
     {
         base.OnInspectorGUI();
 
         GUILayout.Space(5);
         IsOpen = EditorGUILayout.BeginFoldoutHeaderGroup(IsOpen, "Score list (" + scoreList.scores.Count + ")", EditorStyles.foldoutHeader);
         foreach (Score score in scoreList.scores)
         {
             EditorGUILayout.BeginVertical(EditorStyles.helpBox);
             EditorGUI.BeginDisabledGroup(true);
             score.percent = EditorGUILayout.FloatField("Score percent", score.percent);
             if (IsOpen)
             {
                 score.material = EditorGUILayout.ObjectField("2D Sprite", score.material, typeof(Material), true) as Material;
                 score.sprite = EditorGUILayout.ObjectField("2D Sprite", score.sprite, typeof(Sprite), true) as Sprite;
             }
             EditorGUI.EndDisabledGroup();
             if (IsOpen)
                 if (GUILayout.Button("Remove this"))
                     delete = score;
             EditorGUILayout.EndVertical();
         }
         if (delete.NotEqualsNull())
         {
             scoreList.scores.Remove(delete);
             score = delete;
             delete = null;
             EditorUtility.SetDirty(scoreList);
         }
 
         EditorGUILayout.EndFoldoutHeaderGroup();
         GUILayout.Space(10);
         EditorGUILayout.LabelField("Add new Score");
         score.percent = EditorGUILayout.Slider("Score percent", score.percent, 0, 1);
         score.material = EditorGUILayout.ObjectField("2D Sprite", score.material, typeof(Material), true) as Material;
         score.sprite = EditorGUILayout.ObjectField("2D Sprite", score.sprite, typeof(Sprite), true) as Sprite;
         if (GUILayout.Button("Add"))
         {
             scoreList.scores.Add(score);
             EditorUtility.SetDirty(scoreList);
             score = new Score();
         }
     }
 }

After that, I can add my Score to scores and seen like it work! But it don't working properly after all. Whenever I hit "Play", all my data gone away! I try store data after hit Play but it's still not working I try figure out by myself on Internet, on similar problem I find but after all, I can't see what wrong in my code.