Bitmap cannot be used as a mask in html5

This was marked as “Moved to “Recently Completed””.
This was marked as “Closed”.

However, a simple test of using a bitmap as a mask in html5 (openfl 8.9.6) shows nothing on the page. You can mask a bitmap with a shape, but not a shape with a bitmap.

class SimpleTestMask extends Sprite {

public function new() {

        var container:Sprite = new Sprite();

        var sh:Shape = new Shape();;, 0, 200);;

        var bmd:BitmapData = new Match02(0, 0);
        var bmp:Bitmap = new Bitmap(bmd);
        //container.mask = sh; // This works - bitmap is masked by shape
        container.mask = bmp; // This does not - cannot use bitmaps as masks???


class Match02 extends BitmapData { }

FWIW - I tried both canvas and webgl compiles