I've added Azure ADB2C login for members to my umb10 site, but I have a few issues:

a) I can only get the sign in to work if I add this bit of code:

signInManager.SignInAsync(user, true) 

during the OnTicketReceived event handler. Without it, IsAutheticated is always false for the user.

b) the OnAutoLinking & OnExternalLogin callbacks in my AzureB2CMembersExternalLoginProviderOptions class never seem to be fired

c) if i retrieve a user with:

memberManager.FindByNameAsync(name).GetAwaiter().GetResult()

the user doesn't have any roles assigned to it (but it does if i retrieve the same user with:

memberService.GetByEmail(email)

This is my code:

public static IUmbracoBuilder ConfigureAuthenticationMembers(this IUmbracoBuilder builder)
{
    builder.Services.ConfigureOptions<AzureB2CMembersExternalLoginProviderOptions>();
    builder.AddMemberExternalLogins(logins =>
    {
        logins.AddMemberLogin(
            membersAuthenticationBuilder =>
            {
                membersAuthenticationBuilder.AddMicrosoftAccount(
                    membersAuthenticationBuilder.SchemeForMembers(AzureB2CMembersExternalLoginProviderOptions.SchemeName),
                    options =>
                    {
                        var config = builder.Config;

                        options.Scope.Add("openid");
                        options.Scope.Add("profile");
                        options.Scope.Add("email");
                        options.Scope.Add("phone");
                        options.Scope.Add("address");

                        options.CallbackPath = "/signin-microsoft";
                        options.ClientId = "xxxx";
                        options.ClientSecret = "xxxx";
                        options.SaveTokens = true;

                        //options.Events.OnRedirectToAuthorizationEndpoint = OnRedirectToAuthorizationEndpoint;
                        options.Events.OnTicketReceived = OnTicketReceived;
                        options.Events.OnAccessDenied = OnAccessDenied;
                    });
            });
    });

    return builder;
}

private static Task OnTicketReceived(TicketReceivedContext arg)
{
    var logger = arg.HttpContext.RequestServices.GetService<ILogger>();
    try
    {
        var objectidentifier = arg.Principal?.Claims.FirstOrDefault(c => c.Type.Equals(Constants.Identity.NameIdentifierSchema))?.Value;
        if (!string.IsNullOrEmpty(objectidentifier))
        {
            var state = arg.Properties.Items[Constants.Identity.State];

            logger.Information($"Signed in ADB2C user: [{objectidentifier}]");

            //Now, make sure a membership user is in sync with the currently logged in user
            UpdateOrInsertMembershipMember(objectidentifier, arg.HttpContext);

            IMemberSignInManager signInManager = arg.HttpContext.RequestServices.GetService<IMemberSignInManager>();
            IMemberManager memberManager = arg.HttpContext.RequestServices.GetService<IMemberManager>();
            var user = memberManager.FindByNameAsync(objectidentifier).GetAwaiter().GetResult();

            // Roles are empty at this point !!!
            var roles = user.Roles;

            signInManager.SignInAsync(user, true);

            var umbracoContextFactory = arg.HttpContext.RequestServices.GetService<IUmbracoContextFactory>();

            using (var ctx = umbracoContextFactory.EnsureUmbracoContext())
            {
                var portal = ctx.UmbracoContext.Content.GetAtRoot().First(x => x.IsDocumentType(Portal.ModelTypeAlias));
                var accountPending = portal.FirstChild<AccountPending>();
                arg.Response.Redirect(accountPending.Url());
            }
        }
        else
        {
            logger.Error("Unable to retrieve the object identifier from the ADB2C Identity");
        }
    }
    catch (Exception e)
    {
        logger.Error(e.Message, e);
    }

    return Task.FromResult(0);
}

private static async Task UpdateOrInsertMembershipMember(string objectidentifier, HttpContext context)
{
    var configuration = context.RequestServices.GetService<IConfiguration>();
    var appSettings = configuration.GetSection("AppSettings");

    var email = $"{objectidentifier}@{appSettings["ida-UmbracoMemberEmail"]}";

    var memberService = context.RequestServices.GetService<IMemberService>();
    var publishedSnapshotAccessor = context.RequestServices.GetService<IPublishedSnapshotAccessor>();

    var member = memberService.GetByEmail(email);
    if (member != null)
    {
        member.Username = objectidentifier;
        member.Name = objectidentifier;
        member.LastLoginDate = DateTime.Now;
        memberService.Save(member);
    }
    else
    {
        member = memberService.CreateMember(objectidentifier, email, objectidentifier, AzureAdmember.ModelTypeAlias);
        member.LastLoginDate = DateTime.Now;
        member.SetValue(AzureAdmember.GetModelPropertyType(publishedSnapshotAccessor, x => x.Language).Alias, Constants.Culture.BaseCulture);
        memberService.Save(member);

        //After the user was created add it to the New role.
        memberService.AssignRole(objectidentifier, Constants.MemberGroups.New);
    }

    // Roles are correct when user is retrieved from the memberservice
    var rolesTest = memberService.GetAllRoles(objectidentifier);
}

Note: I'm using .AddMicrosoftAccount and NOT .AddOpenIdConnect