using pnp.framework in MVC web app with .net framework 4.6.x hangs

[dean118]

Using pnp.framework with .net framework 4.6.x in console and win from application works. However using pnp.framework in MVC web app with .net framework 4.6.x hangs, when calling method
public async Task GetContextAsync(string siteUrl, CancellationToken cancellationToken)

Tested accessing SPO with certificate app-only authentication, debugging in, specifically happens on .ConfigureAwait(false) in
catch block
Bolded below.

            case ClientContextType.AzureADCertificate:
                {

#pragma warning disable CS0618 // Type or member is obsolete
var accounts = await confidentialClientApplication.GetAccountsAsync().ConfigureAwait(false);
#pragma warning restore CS0618 // Type or member is obsolete

                    try
                    {
                        authResult = await confidentialClientApplication.AcquireTokenSilent(scopes, accounts.First()).ExecuteAsync(cancellationToken).ConfigureAwait(false);
                    }
                    catch
                    {
                        authResult = await confidentialClientApplication.AcquireTokenForClient(scopes).ExecuteAsync(cancellationToken)**.ConfigureAwait(false)**;
                    }
                    if (authResult.AccessToken != null)
                    {
                        return BuildClientContext(confidentialClientApplication, siteUrl, scopes, authenticationType);
                    }
                    break;
                }