Disappearing Sage Help entries in Jupyter Help menu when swithching w Lab

[Seth Chaiken]

With Sage 10.4 built locally, Sage Jupyter notebooks started just after server start show, under the Help menu, the many items for Sage help below Jupyter help; but when JupyterLab is activated, it's Help menu shows nothing for Sage, there is still no Sage Help items when switching back to Notebook.  Also, after activating JupyterLab, new notebooks opened from the Home window do not have the Sage items under their help menu.

Let me know if more info about my setup is needed.