Fixed reflection probe placement

Editor/ReflectionProbeVolumeEditor.cs

@@ -88,6 +88,8 @@ namespace Utils
                         }
                     }
                 }
+
+                Undo.RegisterFullObjectHierarchyUndo(reflectionProbeVolume.gameObject, "Place Reflection Probes");
             }
 
             private void CheckSquare(Vector3[,] data, int size, int voxelSize, float threshold, float blendDistance, Transform transform)