Jupyter Configurable nbextensions list is empty

Question

I installed conda install -c conda-forge jupyter_nbextensions_configurator and ran jupyter nbextensions_configurator enable --user in my venv, but the nbextensions menu is empty. I've restarted notebook a few times, no luck. How can I get the menu to show up so that I can click and select TOC, etc.?

System details:

Windows 10, Firefox
conda 4.8.2
Python 3.8.3
jupyter 1.0.0 pypi_0 pypi
jupyter_client 6.1.3 py_0 conda-forge
jupyter_console 6.1.0 py_1 conda-forge
jupyter_contrib_core 0.3.3 py_2 conda-forge
jupyter_core 4.6.3 py38h32f6830_1 conda-forge
jupyter_nbextensions_configurator 0.4.1 py38_0 conda-forge

(myenv) C:\path>jupyter nbextension list
Known nbextensions:
  config dir: C:\path\.jupyter\nbconfig
    notebook section
      nbextensions_configurator/config_menu/main enabled
      - Validating: problems found:
        - require?  X nbextensions_configurator/config_menu/main
      jupyter-js-widgets/extension disabled
      jupyter-vega/index disabled
    tree section
      nbextensions_configurator/tree_tab/main enabled
      - Validating: problems found:
        - require?  X nbextensions_configurator/tree_tab/main
  config dir: C:\path\anaconda3\envs\myenv\etc\jupyter\nbconfig
    notebook section
      jupyter-js-widgets/extension enabled
      - Validating: ok
      jupyter-vega/index enabled
      - Validating: problems found:
        - require?  X jupyter-vega/index
      nbextensions_configurator/config_menu/main enabled
      - Validating: problems found:
        - require?  X nbextensions_configurator/config_menu/main
    tree section
      nbextensions_configurator/tree_tab/main enabled
      - Validating: problems found:
        - require?  X nbextensions_configurator/tree_tab/main

Answer 1

I found the answer here, in an open issue on Github

I ran the following in Anaconda prompt:

conda install -c conda-forge jupyter_contrib_nbextensions
jupyter nbextensions_configurator enable --user

(note that conda install -c conda-forge jupyter_nbextensions_configurator had already been run in the prompt)

And then launched notebook and the extensions were available: