Why is the SpriteRenderer color not updating at runtime?

Question

I have a GameObject with a SpriteRenderer and its default color is set to white. At runtime I'm setting the color to Color.gray and for some reason it is not updating at runtime to the new gray tint. I have confirmed that the objects in my script are correct because the sprite completely disappears if I set enabled to false and if I have the object selected in the editor and play, the color changes in the Inspector but does not update in the Game View.

This is my simple script

public class GameManager : MonoBehaviour
{
    public SpriteRenderer Player1;
    public SpriteRenderer Player2;

    public void SetTurn(bool isPlayer1)
    {
        this.Player1.color = Color.gray;
        this.Player2.color = Color.gray;

        if (isPlayer1)
            this.Player1.color = Color.white;
        else
            this.Player2.color = Color.white;
    }
}

SetTurn is being called from a different script in its Update on a mouse click; I have verified that the function is actually running. I've also tried simplifying this to:

public class GameManager : MonoBehaviour
{
    public SpriteRenderer Player1;
    public SpriteRenderer Player2;

    private void Update()
    {
        this.Player1.color = Color.red;
    }
}

That doesn't even work. There are no warnings and no errors in the console either. I've tried rebooting, rebuilding, quitting and restarting, running on a different machine and running on a completely different platform... nothing works.

Any idea what I'm doing wrong? Again, the color changes in the Inspector at runtime but does not in the Game View. Also, if I change the color manually in the Inspector at runtime the Game View does change color, it just refuses to do it from the script.

EDIT

I've also tried using Color32 just to cover my bases and that doesn't work, as I expected it wouldn't.

UPDATE

I completely removed the script and made a new script that I attached directly to the GameObject itself and that doesn't even work.

public class test : MonoBehaviour
{
    private SpriteRenderer m_Renderer;

    void Start()
    {
        this.m_Renderer = this.GetComponent<SpriteRenderer>();
    }

    void Update()
    {
        this.m_Renderer.color = Color.black;
        Debug.Log("COLOR BLACK");
    }
}

The console displays "COLOR BLACK" so I know the Update is being called but still no color change in Game View or Scene View but it does change in the Inspector

UPDATE 2

I narrowed it down but still haven't solved it. I'm using the 2d experimental build 5.5.0a6. I installed the current stable version 5.4.2f2 and the problem does not exist! So, the problem has something to do with the SpriteRenderer in version 5.5.0a6. I'm trying to find out what the issue is, and I hope this gets fixed soon.

UPDATE 3 Here is a link to 2 simple projects that illustrate the issue. One for version 5.5.0a6 which DOES contain the issue and the exact same project for version 5.4.2f2 which DOES NOT contain the issue.

Sample Projects

Answer 1

Just update for someone who may want the answer to this question. In version 2019.1.12f1 of Unity. We have to set 1 more Alpha value after we select the color in the Editor

Click to see how to set Alpha value after select color Then we can use the code normally like:

public Color pink;
public Color purple;
void SetRandomColor() {
        int ran = Random.Range(0, 1);
        Debug.Log("RANDOM: " + ran);
        switch (ran) {
            case 0:
                sr.color = pink;
                break;
            case 1:
                sr.color = purple;
                break;
        }
    }