OnValidate now working and not necesary to call CleanUp on disable anymore.

Assets/ScriptableRenderLoop/HDRenderLoop/HDRenderLoop.cs

         TextureCache2D m_CookieTexArray;
         TextureCacheCubemap m_CubeCookieTexArray;
 
-        private void OnEnable()
+        private void OnValidate()
-            // TODO: Design workaround for OnValidate being missing on ScriptableObject
-            Rebuild();
-        }
-
-        private void OnDisable()
-        {
-            // TODO: Rework ScriptableRenderLoop Lifecycle 
-            //CleanUp();
         }
 
         public override void Rebuild()

Assets/ScriptableRenderLoop/fptl/FptlLighting.cs

         private Texture2D m_LightAttentuationTexture;
         private int m_shadowBufferID;
 
-        public override void Initialize()
+        private void OnValidate()
-        private void OnEnable()
+        public override void Initialize()
-        }
-
-        private void OnDisable()
-        {
-            // TODO: Rework ScriptableRenderLoop Lifecycle
-            //CleanUp();
         }
 
         public override void Cleanup()