problem with coroutine not executing code

I have a black image over the screen. When conditions are met, the animation changes the transparency from transparent to solid, creating a fade-out effect. This works fine and displays the "a" values changing from 0 to 1. But after fading out, the code to change scenes is not activated until "faded" is displayed over 100 times. Basically, it fades, then gets stuck there for a few seconds before the scene actually changes. Why is it displaying "Faded" so many times but not firing off the scene change?

if (isDead && isGrounded)
{
StartCoroutine(Fading());
}

IEnumerator Fading()
{
Debug.Log(black.color.a);
anim.SetBool("Fade", true);
yield return new WaitUntil(() => black.color.a >.9);
Debug.Log("faded");
SceneManager.LoadScene("LevelFail");

}