Viewer widget not visible in Jupyter Notebook on CodeOcean

## Overview

`itkwidgets.view` produces output but does not show the expected 3D image.

## Steps to reproduce

1. In a clean environment, `pip install itk itkwidgets[notebook]==1.0a23`
2. Run `Hello3DWorld.ipynb`

## Expected Behavior

`itkwidgets.view` depicts 3D volume rendering

## Observed Behavior


## Environment

Python 3.8.5
ITK v5.3.0
itkwidgets 1.0a23
Ubuntu 20.04

Docker image: registry.codeocean.allenneuraldynamics.org/codeocean/jupyterlab:3.0.9-miniconda4.9.2-python3.8-ubuntu20.04

## Other Notes

Behavior is observed in a clean environment run via CodeOcean reproducible platform.

Is this maybe an environment issue, and if so what are some things that could be going wrong or some possible steps to resolve? I think I've observed this issue in my local setup before but am uncertain what steps I took to resolve it. Once a resolution is identified, could it be added to an FAQ section in documentation?

EDIT: Note that the ImJoy extension seems to load successfully


The local browser console shows the errors below. The "refused to execute script" error appears regardless of whether `itkwidgets` is installed when the notebook launches.