Error loading Jupyter Notebook from a child directory

[NesquikMike]

Since I have updated to macOS 11.4 Big Sur (I have managed to fix all of the Python issues that Big Sur created on my computer. This article is helpful for that), I've been unable to open the Jupyter Notebooks in any of the child directories of where I start my Jupyter Notebook.

I can however open notebooks in the same directory as where I had started my Jupyter Notebook instance.

Here is a screenshot of the error message:

Here also is the error message I get in the terminal when trying to open a new notebook in a child directory:

[W 20:18:51.458 NotebookApp] 404 GET /nbextensions/widgets/notebook/js/extension.js?v=20210723201825 (::1) 2.560000ms referer=http://localhost:8888/notebooks/0001_analysis/Untitled2.ipynb?kernel_name=python3

I use pyenv and poetry to manage my python environment and packages. I have the local version of python set to Python 3.8.2.

Here are my poetry dependencies in my pyproject.toml:

[tool.poetry.dependencies]
python = "^3.8

[tool.poetry.dev-dependencies]
pandas = "^1.3.0"
scikit-learn = "^0.24.2"
notebook = "^6.4.0"
seaborn = "^0.11.1"
ipykernel = "^6.0.1"

I've tried this on multiple browsers and with different versions of notebook and had no luck. Would be great to fix this, as it is inconvenient having to create new notebook instances when I need to open notebooks in different child directories of my project.