Disable UI button does not work when calling function directly, does when calling intermediate function that Invokes disable with a delay of 0

Trying to understand the Unity UI system.

I have a panel that contains a button that should hide the panel.

When I wire the button up to the method that hides the panel, I can see in the console that the method is called but it has no effect.

However if I call an intermediate method from the button that uses the monobehavior Invoke method to call the disable method, even with a delay of 0, it does work.

Does not work:

    public void DisableUI(string sentBy)
    {
        print("disabling UI from: " + sentBy);
        _panel1.gameObject.SetActive(false);
        _secretPanel.gameObject.SetActive(true);
        _uiActive = false;
    }

Does work:

    public void DisableUI(string sentBy)
    {
        print("disabling UI from: " + sentBy);
        Invoke(nameof(SetUiInactive), 0f);
    }

    private void SetUiInactive() 
    {
        _panel1.gameObject.SetActive(false);
        _secretPanel.gameObject.SetActive(true);
        _uiActive = false;
    }

Note that calling the function directly from another script does work as expected.

Can anyone explain what's going on?

Thanks for any help.