I did a fresh install of Jupyter Notebook today. It is working as it should be.
After that I tried installing nbextensions but I run into problems when tying to execute:
jupyter contrib nbextension install --user
I Get the following error:
ImportError: cannot import name 'create_prompt_application' from 'prompt_toolkit.shortcuts' (/home/pi/.local/lib/python3.7/site-packages/prompt_toolkit/shortcuts/__init__.py)
If I start a notebook I can see the extensions tab but only two modules are shown.