Android - Setting RadioButton dot with setButtonDrawable() doesn't work

Question

Simple question, perplexing problem.

I am making a custom dot indicator for an android RadioButton that subclasses AppCompatRadioButton. I just want to change the dot indicator not the whole background. It seems like setButtonDrawable() should do the trick...

class McRadioButton @JvmOverloads constructor(
    context: Context, attrs: AttributeSet? = null
) : AppCompatRadioButton(context, attrs)
{
    init { 
        setButtonDrawable(R.drawable.mc_radio_button)
        invalidate()
        requestLayout()
    }
}

mc_radio_button.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Shapes are just examples to illustrate the problem -->

<selector
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item android:state_enabled="true" android:state_checked="true" >
        <shape android:shape="oval">
            <solid android:color="@android:color/holo_red_dark"/>
        </shape>
    </item>

    <item android:state_enabled="true" android:state_checked="false">
        <shape android:shape="oval">
            <solid android:color="@android:color/holo_blue_bright"/>
        </shape>
    </item>

    <item android:state_enabled="false" android:state_checked="true">
        <shape android:shape="oval">
            <solid android:color="@android:color/holo_green_light"/>
        </shape>
    </item>

    <item android:state_enabled="false" android:state_checked="false">
        <shape android:shape="oval">
            <solid android:color="@android:color/holo_orange_light"/>
        </shape>
    </item>
</selector>

When I use my McRadioButtons inside a RadioGroup I only get the android:text I added to the McRadioButton xml instance. I dont see the dot buttons at all.

Again, setting the background is not what I want. Doing so shows large colored ovals under the text. I just want to change the dot indicators. Also, I dont want to merely change the dot color as it does in the above example. I can use a tint to do that. My actual dot will be more complex. But if I get this working then I can do the rest. How do i set the RadioButton dot via xml drawables? Thanks

    setCompoundDrawablesWithIntrinsicBounds(R.drawable.mc_radio_button,0,0,0)

does nothing at all.

This should be simple. What am I doing wrong?