ISerializationCallbackReceiver can help control how data is Serialized and Deserialized between app restarts. Here is some notes on using it.

HowTo_ISerializationCallbackReceiver.cs

//Make all reffs are already serialized that are to be used when OnAfterDeserialize() is called.

public bool IsReady { get => isInitialized && Cells.Count > 0; }
public Config_CellData Storage { get => cellDataStorage; }
public bool IsInitialized { get => isInitialized; private set => isInitialized = value; }
[SerializeField]
private bool isInitialized = false;
[SerializeField]
private Config_CellData cellDataStorage = null;

[SerializeField]
private GameManager gameSifu = null;
private MapManager mapSifu = null;

public List<CellData> Cells = new List<CellData>();
public List<CellData> BossCells  = new List<CellData>();
public List<CellData> ElevatorCells = new List<CellData>();
public List<CellData> TownCells = new List<CellData>();

public void OnBeforeSerialize()//Called almost every dirty frame in Editor
{
    //SaveCellData(); or not. Do loading first before saving to see if its the result you want.
    if (!isInitialized)
        return;

    Log(string.Format("CellManager: Begin Serialization for {0} Land, {1} Towns, {2} Elevators, {3} Bosses",
        cellDataStorage.Mintable.Count, cellDataStorage.Towns.Count, cellDataStorage.Elevators.Count, cellDataStorage.Bosses.Count));
}
public void OnAfterDeserialize()//This special function is called when Unity loads this asset for the first time
{
    gameSifu = GameManager.Instance;//Will not work, Instance uses FindGameObjectOfType and 
    if(gameSifu == null)
    {
        Debug.LogError("Uhoh GameSifu Null, Tell Dencho QUICKLY!");
        return;
    }
    mapSifu = gameSifu.MapSifu;
    if (mapSifu == null)
    {
        Debug.LogError("Uhoh MapSifu Null, Tell Dencho QUICKLY!");
        return;
    }
    if (!mapSifu.IsInitialized)
        mapSifu.InitializeGridSystem();//Populate the GridSystems List
    GridSystems = mapSifu.GridSystems;
    if (cellDataStorage == null)
        return;
    Log(string.Format("CellManager: Begin Deserialization for {0} Land, {1} Towns, {2} Elevators, {3} Bosses", 
        cellDataStorage.Mintable.Count, cellDataStorage.Towns.Count, cellDataStorage.Elevators.Count, cellDataStorage.Bosses.Count));
    mapSifu.Version = cellDataStorage.Version;
    Cells = new List<CellData>();
    for (int i = 0; i < cellDataStorage.Mintable.Count; i++)
    {
        Cells.Add(cellDataStorage.Mintable[i]);
    }
    TownCells = new List<CellData>();
    for (int i = 0; i < cellDataStorage.Towns.Count; i++)
    {
        TownCells.Add(cellDataStorage.Towns[i]);
    }
    ElevatorCells = new List<CellData>();
    for (int i = 0; i < cellDataStorage.Elevators.Count; i++)
    {
        ElevatorCells.Add(cellDataStorage.Elevators[i]);
    }
    BossCells = new List<CellData>();
    for (int i = 0; i < cellDataStorage.Bosses.Count; i++)
    {
        BossCells.Add(cellDataStorage.Bosses[i]);
    }
    TownGroups = new List<TownGroup>();
    for (int i = 0; i < cellDataStorage.TownGroups.Count; i++)
    {
        TownGroups.Add(cellDataStorage.TownGroups[i]);
    }
    IsInitialized = GridSystems.Count > 0 && Cells.Count > 0;
    Debug.Log("CellManager Deserialized!");
}