.net core 3.1HTTP GET returns status code 405 method not allowed

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C#

WebAPI

I have a .Net 3.1 API that runs in a Docker container. I am able to do POST requests (using Postman) successfully to one of the methods but when I attempt a GET to the method below I get

Status Code: 405; Method Not Allowed

This is the method :

PaymentController.cs

[HttpGet]
       public async Task<ActionResult<IEnumerable<PaymentDetailDto>>> GetAsync()
       {
           var items = (await _service.GetAllAsync());
           return Ok(items);
       }

What am I missing?

What I have tried:

In Startup.cs I have already added CORS:

<pre>  public void ConfigureServices(IServiceCollection services)
        {

         
            services.AddControllers();
            services.AddDbContext<ApplicationDbContext>(o => o.UseMySql(Configuration.GetConnectionString("mysqlconnection")));
            services.AddDiscoveryClient(Configuration);
            services.AddCors(c =>
            {
                c.AddPolicy("AllowOrigin", options => options.AllowAnyOrigin());
            });}