NSwag error generating endpoint address

SitesController.cs

namespace nswagtest.Controllers {
    [Produces("application/json")]
    [Route("/api/{subscriptionId}/[controller]")]
    public class SitesController : Controller {

        [HttpGet]
        [ProducesResponseType(typeof(Array), StatusCodes.Status200OK)]
        public IActionResult List(string searchString) {
            return Ok(new[] {"with", "parameter"});
        }

        [HttpGet("/api/sites")]
        [ProducesResponseType(typeof(Array), StatusCodes.Status200OK)]
        public IActionResult ListAll(string searchString) {
            return Ok(new[] {"list", "all"});
        }
    }
}