.NET 6集成Sustainsys.Saml2，从IdP返回后User/Claims为空

我正尝试在新的.NET 6项目中集成Sustainsys.Saml2，但在ACS调用完成后遇到User及claims为空的问题。日志显示已成功处理SAML响应并认证用户，但User.Identity未被填充，IsAuthenticated属性也未设置。我的目标是让应用作为单个外部IdP的SP，不清楚问题所在，寻求帮助。

相关信息 #

1. 框架与包 #

使用.NET 6.0，相关包见截图（原提问附带截图，此处省略）

2. Program.cs配置代码 #

builder.Services.AddIdentity<ApplicationUser, IdentityRole>()
    .AddEntityFrameworkStores<{...context...}>()
    .AddDefaultTokenProviders();

builder.Services.AddAuthentication(opt =>
{
    // Default scheme that maintains session is cookies.
    opt.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;

    // If there's a challenge to sign in, use the Saml2 scheme.
    opt.DefaultChallengeScheme = Saml2Defaults.Scheme;
})
.AddCookie()
.AddSaml2(opt =>
{
    // Us; the Service Provider
    opt.SPOptions.EntityId = new EntityId("https://localhost:34287/Saml2");

    // Single logout messages should be signed according to the SAML2 standard, so we need
    // to add a certificate for our app to sign logout messages with to enable logout functionality.
    opt.SPOptions.ServiceCertificates.Add(new X509Certificate2("Sustainsys.Saml2.Tests.pfx"));

    // Them; the Identify Provider
    opt.IdentityProviders.Add(

        // Fake IdP for testing
        new IdentityProvider(new EntityId("https://stubidp.sustainsys.com/Metadata"), opt.SPOptions)
        {
            LoadMetadata = true
        });
});

3. AccountController代码 #

public AccountController(IConfiguration configuration, SignInManager<ApplicationUser> signInManager, ILogger<AccountController> logger)
{
    _configuration = configuration;
    _signInManager = signInManager;
    _logger = logger;
}

[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult Login()
{
    // Automatic handling is to redirect back to same page after successful
    // login. We don't want that on explicit login.
    var props = new AuthenticationProperties
    {
        RedirectUri = "/"
    };

    return Challenge(props, Saml2Defaults.Scheme);
}

日志信息 #

点击登录按钮后，Saml2日志显示：

info: Sustainsys.Saml2.AspNetCore2.Saml2Handler[0]
      Initiating login to https://stubidp.sustainsys.com/Metadata
info: Sustainsys.Saml2.AspNetCore2.Saml2Handler[0]
      Successfully processed SAML response id84814e90fa344d05876556797416dc41 and authenticated AdminAlmighty

内容的提问来源于stack exchange，提问作者Nick