Should EditorGUILayout.PropertyField work with serializable classes?

I'm trying to create a custom inspector but I when try to display a Serializable class it doesn't show up. It does show the serializable class name as a label with the small foldable arrow next to it but when I try to unfold it, its empty.

At this point I am only trying to replicate the behaviour of the Unity editor, nothing fancy yet. What do I do wrong? How do I get the current behaviour of the editor with serializable classes? (without having to build the gui for each serializable class myself)

The MonoBehaviour for which I am building a custom inspector

 public class SomeComponent : MonoBehaviour
 {
     public ChangeColor SomeColor;
     public ChangeScore SomeScore;
 }

The serializable classes

 [System.Serializable]
 public class ChangeColor 
 {
     public Material Mat;
     public Color To;
 }
 
 [System.Serializable]
 public class ChangeScore 
 {
     public int Points;
     public Transform Position;
 }

The custom inspector

 [CustomEditor(typeof(SomeComponent))]
 public class SomeComponentEditor : Editor
 {
     private SerializedObject m_object;
 
     public void OnEnable()
     {
         m_object = new SerializedObject(target);
     }
 
     public override void OnInspectorGUI()
     {
         m_object.Update();
 
         GUILayout.Label("Some label", EditorStyles.boldLabel);
 
         var prop = m_object.FindProperty("SomeColor");
         EditorGUILayout.PropertyField(prop);
 
         prop = m_object.FindProperty("SomeScore");
         EditorGUILayout.PropertyField(prop);
 
         m_object.ApplyModifiedProperties();
     }
 }