Trouble set the scene active with SceneMananger

I’m trying to set an scene active that was loaded additively but for some reason i cant get to turn active.

SceneManager.LoadScene(sceneName, LoadSceneMode.Additive);
var scene = SceneManager.GetSceneByName(sceneName);
SceneManager.SetActiveScene(scene); // does not set active

My Unity version is 5.3.4f1.

My solution was converting the function to a coroutine and then call the SceneManager.LoadSceneAsync method, then wait the load to finish before set the scene active.

var loading = SceneManager.LoadSceneAsync(sceneName, LoadSceneMode.Additive);
yield return loading;

var scene = SceneManager.GetSceneByName(sceneName);
SceneManager.SetActiveScene(scene);

I guess this is a bug, but i am not sure.