System.ArgumentException: 'Connection string missing required properties endpoint and accesskey. (Parameter 'connectionString')'

Question

This Blazor Server project is a simple chat application using signalR and Azure Active Directory. I am testing locally from my machine before publishing to a server. I am VPN into network. Everything is configured correctly in appsettings.json to point to our Azure test environment, and I have tested successfully with the default Blazor server project against the AAD. However when running the code the following exception is present in Program.cs --

'System.ArgumentException: 'Connection string missing required properties endpoint and accesskey. (Parameter 'connectionString')'

Program.cs:

public class Program
{
    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
}

Startup.cs:

{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddAuthentication(OpenIdConnectDefaults.AuthenticationScheme)
            .AddMicrosoftIdentityWebApp(Configuration.GetSection("AzureAd"));
        services.AddControllersWithViews()
            .AddMicrosoftIdentityUI();

        services.AddSignalR().AddAzureSignalR();

        services.AddAuthorization(options =>
        {
            // By default, all incoming requests will be authorized according to the default policy
            options.FallbackPolicy = options.DefaultPolicy;
        });

        services.AddRazorPages();
        services.AddServerSideBlazor()
            .AddMicrosoftIdentityConsentHandler();
        services.AddResponseCompression(opts =>
        {
            opts.MimeTypes = ResponseCompressionDefaults.MimeTypes.Concat(
                new[] { "application/octet-stream" });
        });
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        app.UseResponseCompression();

        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler("/Error");

            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.UseStaticFiles();

        app.UseRouting();

        app.UseAuthentication();
        app.UseAuthorization();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
            endpoints.MapBlazorHub();
            endpoints.MapFallbackToPage("/_Host");
            endpoints.MapHub<ChatHub>("/chathub");
        });
    }

The appsettings.json:

{
  "AzureAd": {
    "Instance": "https://login.microsoftonline.com/",
    "Domain": "university.edu",
    "TenantId": "xxx",
    "ClientId": "xxxx",
    "CallbackPath": "/signin-oidc"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "Azure": {
    "SignalR": {
      "Enabled": true,
      "ConnectionString": "Connection"
    }
  },
  "AllowedHosts": "*"
}

Secrets.json:

{
  "Azure:SignalR:ConnectionString": "Connection"
}