Serializable custom class with game object not shown

So I want to make a custom plane with editable tiles for a simple 2D tile game. It is a small thing to play around with custom inspector, editor and serializable things.

So I have a MonoBehviour "ManagerScript", a custom class "TiledPlane" containing a gameObject.

Here is the code for the monobehaviour:

 using UnityEngine;
 using System.Collections;
 
 [System.Serializable]
 public class ManagerScript : MonoBehaviour 
 {
     [SerializeField]
     public TiledPlane tiledPlane;
 }

This is the code for the custom class:

 using UnityEngine;
 using System.Collections;
 
 [System.Serializable]
 public class TiledPlane
 {

     <... Some Mesh data ...>
 
     private GameObject m_gameObject;
     public GameObject gameObject
     {
         get
         {
             return m_gameObject;
         }
         private set
         {
             m_gameObject = value;
         }
     }
 
     public TiledPlane()
     {
         CreateDefaultMesh();
     }
 
     public void CreateDefaultMesh()
     {
         <... Some Mesh data ...>
 
         m_Mesh = new Mesh();
         m_Mesh.name = "TilePlaneMesh";
         m_Mesh.vertices = m_Vertices;
         m_Mesh.normals = m_Normals;
         m_Mesh.uv = m_UVs;
         m_Mesh.triangles = m_Triangles;
 
         if (m_gameObject == null)
             m_gameObject = new GameObject("TiledPlane", typeof(MeshFilter), typeof(MeshRenderer));
         m_gameObject.GetComponent<MeshFilter>().mesh = m_Mesh;
     }
 }

Evertime I make changes to my code and switch back to Unity a new GameObject is created and the TiledPlane of the ManagerScript is null. Simply the constructor of TiledPlane is called once.