Unity 进度条卡死

网上大部分来源都是如下代码
这个代码会引起导出 Android 包时，加载场景卡死

public void Load(int id)
{
	StartCoroutine("LoadLevelAsync", id);
}

IEnumerator LoadLevelAsync(int levelId)
{
	int displayProgress = 0;
	int toProgress = 0;
	yield return new WaitForEndOfFrame();
	Level lev = LevelMng.Instance.GetItem(levelId);
	mAsync = SceneManager.LoadSceneAsync(lev.Scene);
	mAsync.allowSceneActivation = false;
	while (mAsync.progress < 0.9f)
	{
		toProgress = (int)mAsync.progress * 100;
		while (displayProgress < toProgress)
		{
			++displayProgress;
			LoadingWnd.Instance.UpdateProgress(displayProgress);
			yield return new WaitForEndOfFrame();
		}
		yield return new WaitForEndOfFrame(); //注意如果少了这句话，就是死循环
	}
	toProgress = 100;
	while (displayProgress < toProgress)
	{
		++displayProgress;
		LoadingWnd.Instance.UpdateProgress(displayProgress);
		yield return new WaitForEndOfFrame();
	}
	mAsync.allowSceneActivation = true;
	yield return new WaitForEndOfFrame();
	OnLoadFinishedEx(lev);
}

这个问题会导致有几率发生死循环
加上那句后面带注释的话，就不会死循环了