Hello Adam,
Thanks for your question.
This is a result of an intermittent issue sometimes caused by unavailable capacity. It should work very soon. Try clicking on the Power button in the browser to reset of Azure Cloud Shell and shold resolve your issue
See: https://learn.microsoft.com/en-us/azure/cloud-shell/troubleshooting
You can mark it 'Accept Answer' and 'Upvote' if this helped you
Regards,
Abiola