why Net core return 0 to angular?

I have an app with angular and net core web api 3. The problem I have is that when the token expires in angular I get a status code 0, but when using postman it effectively returns the code 401 (unauthorized). What could be happening? Thank you very much for your help.

Start.cs

public void ConfigureServices(IServiceCollection services)
    {
        var appSettingsJson = AppSettingsJson.GetAppSettings();
        var tokenKey = appSettingsJson["Token:Key"];
        services.AddMvc()
               .SetCompatibilityVersion(CompatibilityVersion.Version_3_0)
               .AddNewtonsoftJson(ConfigureJson).AddExtensions();
        services.AddSignalR();
        services.AddCors(options =>
        {
            options.AddPolicy("EnableCORS", builder => { builder.WithOrigins("*").AllowAnyHeader().AllowAnyMethod(); });
            options.AddPolicy("NoRestrictions", builder => { builder.WithOrigins("*").AllowAnyHeader().AllowAnyMethod(); });
        });

        services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
        services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
         .AddJwtBearer(options =>
         {
             options.TokenValidationParameters = new TokenValidationParameters
             {
                 ValidateIssuer = true,
                 ValidateAudience = true,
                 ValidateLifetime = true,
                 ValidateIssuerSigningKey = true,
                 ValidIssuer = "http://localhost:5000",
                 ValidAudience = "http://localhost:5000",
                 IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(tokenKey))
             };
         });
        services.AddControllers();
    }



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

        if (env.IsDevelopment()) app.UseDeveloperExceptionPage();
        else app.UseHsts();
        app.Use(async (ctx, next) =>
        {
            await next();
            if (ctx.Response.StatusCode == 204)
            {
                ctx.Response.ContentLength = 0;
            }
        });
        app.UseRouting();
        app.UseAuthorization();
        app.UseCors("EnableCORS");
        app.UseAuthentication();
        app.UseHttpsRedirection();
        //app.UseMvc();
        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
            endpoints.MapHub<NotifyHub>("notify").RequireCors("EnableCORS");
            endpoints.MapHub<NotifyActionHub>("notifyaction").RequireCors("EnableCORS");
        });
    }