Custom Inspector changes not updating target in Edit Mode

I have a custom inspector for a UI component that I wrote which builds a polygon mesh. My problem is that when I change one of the values in the custom inspector during edit time, the target component doesnt reflect those changes. However when I change one of the public variables on the target script itself the changes are shown immediately. Heres my code:

 [CustomEditor(typeof(RegularPolygonGraphic))]
 public class RegularPolygonEditor : Editor
 {
     RegularPolygonGraphic Target;
 
     public override void OnInspectorGUI()
     {
         if(target != null)
         {
             Target = target as RegularPolygonGraphic;
         }
 
         DrawDefaultInspector();
 
         if(Target.Puncture)
         {
             EditorGUILayout.BeginHorizontal();
             GUILayout.Label("Thickness");
             Target.Thickness = EditorGUILayout.Slider(Target.Thickness, 0f, 1f);
             Undo.RecordObject(Target, "Set Thickness");
             EditorGUILayout.EndHorizontal();
         }
     }
 }

Now when I move the slider in the inspector around, the RegularPolygonGraphic target doesnt reflect those changes. However if I modify any other public in the RegularPolygonGraphic script that isnt set by the custom inspector, it updates correctly. I have the same problem in a lot of other scripts which need a custom inspector so simply making the Thickness variable public on the target component isnt an option. Thanks for your help! EDIT: If it helps, the target script is doing most of the work inside OnPopulateMesh(VertexHelper vh) which is overriding that method from the Graphic class.