Can not migrate Database

Hello. I don't know how to just ask the question.

When I run update-database, a database is created. However, without the table __Migrations (or whatever its name was). The database is up-to-date.
When I then execute update database, the above table is created. but has only the first entry. I think because the update stopped there. Who can help?

 public async Task SeedAsync()
        {

            if (!DBContext.Database.EnsureCreated())
                DBContext.Database.Migrate();

        }

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, DataService seeder)
        {
            loggerFactory.AddFile("Logs/myapp-{Date}.txt");
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseWebpackDevMiddleware(new WebpackDevMiddlewareOptions
                {
                    HotModuleReplacement = true
                });
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }
            app.UseDeveloperExceptionPage();
            app.UseStaticFiles();


            app.UseAuthentication();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
            // here you can see we make sure it doesn't start with /api, if it does,
            // it'll 404 within .NET if it can't be found
            app.MapWhen(x => !x.Request.Path.Value.StartsWith("/api"), builder =>
            {
                builder.UseMvc(routes =>
                {
                    routes.MapSpaFallbackRoute(
                        name: "spa-fallback",
                        defaults: new { controller = "Home", action = "Index" });
                });
            });


            seeder.SeedAsync().Wait();
        }