Editor extensions completely broken in 5.3.3f1

  using UnityEditor;
  using UnityEngine;
  
  namespace Assets.Editor {
      public class GenerateMaterialsMenuItem {
          [MenuItem("Tools/Generate Materials %g")]
          private void DoStuff() {
              Debug.Log("hi");
          }
      }
  }
  

This is placed in Assets/Editor but it does not show the custom menu item as expected. Is this a known issue and will it be fixed in later releases? Thanks