.NET + Angular Template API Controller Route not working (404)

When I used This Template:

Template

for an Angular Frontend .NET Backend. But when I created an API Controller like this in the Controller Directory:

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;

namespace API.Controllers
{
    [Route("[controller]")]
    [ApiController]
    public class TestController : ControllerBase
    {

        [HttpGet]
        public int Get()
        {
            return 0;
        }
    }
}

I always get 404 Not Found in Postman with query "https://localhost:44490/Test" even though the "WeatherForecastController" template that was already in the Project works fine. I tried the TestController in another Template that is just the .NET Backend and it works fine, I get a normal 200 back...

I also tried a 1 to 1 copy of the WeatherForecastController the Template came with but that also did not Work, I think the Program does not even get to the Controller so I guess there is something wrong with the routing setup. Im new to .Net so I might just have overseen something.

Any help is greatly appreciated.

This is the Program.cs that came with the Project:

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

builder.Services.AddControllers();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();


app.MapControllerRoute(
    name: "default",
    pattern: "{controller}/{action=Index}/{id?}");

app.MapFallbackToFile("index.html");

app.Run();