Blazor Login - Access to email in claims

I have added Auth0 to a Blazor web app following the steps described here How to Build and Secure Web Applications with Blazor

The app works fine and the login/logout experience works as intended.

I notice that the claims on the login does not include the email address which I need for my application.

I tried to add this with a custom action using the following code (my application just uses social connections)

exports.onExecutePostLogin = async (event, api) => {
  if (event.authorization)
    const namesp = "";

This does not appear to have had any effect as the claim does not appear.

Any ideas on how I can get the email in the claims info?