.NET Core 2.2 CORS 不允许请求

我已经检查了其他几个与此有关的线程，但仍然无法弄清楚这一点。我希望允许任何来源、标头、方法等访问我的 .NET Core 2.2 API。

public void ConfigureServices(IServiceCollection services)
    {
        services.AddCors();
        services.AddMvc();  
... 

public void Configure(IApplicationBuilder app, IHostingEnvironment env, IApplicationLifetime lifetime, IDistributedCache cache)
    {
        app.UseCors(builder => builder.AllowAnyOrigin()
        .AllowAnyMethod()
        .AllowAnyHeader()
        .AllowCredentials());

我确保首先在ConfigureServices 和Configure 中调用CORS 方法。我在本地和服务器上对此进行测试，并在 Chrome 中得到相同的错误。

Access to XMLHttpRequest at 'https://xxxxx.azurewebsites.net/api/Employees/getCurrentEmployee' from origin 'https://xxxxxxxxxx.azurewebsites.net' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

在ConfigureServices方法中

services.AddCors(options =>
            {
                options.AddPolicy("CorsPolicy",
                    builder => builder
                    .SetIsOriginAllowed((host) => true)
                    .AllowAnyMethod()
                    .AllowAnyHeader()
                    .AllowCredentials());
            });

在配置方法中

app.UseCors("CorsPolicy");