"no operations defined in spec" in .net 5.0

[JoAlnilam]

Hi I am using version 6.1.3 with .net core 5.0 web api project. I keep getting "no operations defined in spec" although my controllers are correctly constructed. So generator doesn't discover api in the dll. Could it be 5.0 combability issue? Here is a set I have:

public void ConfigureServices(IServiceCollection services)
{
    services.AddRouting(options => options.LowercaseUrls = true);

    services.AddApiVersioning(options =>
    {
        options.ReportApiVersions = true;
        options.ApiVersionReader = new UrlSegmentApiVersionReader();
    });

    services.AddControllers();

    services.AddApiVersioning();

    services.AddMvcCore().AddApiExplorer();

    services.AddSwaggerGen(c =>
    {
        c.SwaggerDoc("v1", new OpenApiInfo { Title = "My API", Version = "v1" });
    });
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env) {

    app.UseForwardedHeaders(new ForwardedHeadersOptions { ForwardedHeaders = ForwardedHeaders.All });

    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }

    app.UseMiddleware(typeof(ExceptionsHandlingMiddleware));

    app.UseHealthChecks("/health");

    app.UseHttpsRedirection();

    app.UseCors(policy => policy.AllowAnyOrigin().AllowAnyHeader());

    app.UseSwagger();

    app.UseSwaggerUI(c =>
    {
        c.SwaggerEndpoint("v1/swagger.json", "My REST API");
    });

    app.UseRouting();

    app.UseEndpoints(endpoints => { endpoints.MapControllers(); });
}

[ApiController]
[Route("api/[controller]")]
public class ModelsController : ControllerBase
{