Altair charts don't work in offline mode

[DavidFrench]

Hello,

We are running a secure Databricks environment (no internet access) within an Azure Virtual Desktop and are currently unable to get any charts to display. They work if we access the environment from outwith the AVD, but not when we access it from within the AVD.

Some example code (from the altair documentation😞

import altair as alt
import pandas as pd

source = pd.DataFrame({
    'a': ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I'],
    'b': [28, 55, 43, 91, 81, 53, 19, 87, 52]
})

chart = alt.Chart(source).mark_bar().encode(
    x='a',
    y='b'
)

jchart = alt.JupyterChart(chart)
jchart

This leads to the error message "Could not load module anywidget from https://cdn.jsdelivr.net/npm/anywidget@~0.9.*/dist/index.js. The widget author may have not published the widget JavaScript or there may have been a network error.", although the anywidget package is already installed.

Can anyone suggest anything we could try?