setMask across nested containers is broken sometimes

Bugs
1 
const holder = new Rectangle({width:400, height:200, corner:50}).center();
// so when adding pen to holder, we can interact with it 
holder.mouseChildren = true;

const pen = new Pen({
    size:12,
	color:red,
    cropScale:2
}).addTo(holder); // add to holder so mousedown of MotionController is only on holder
pen.paper.setMask(holder); // was not working - used holder.shape instead but should not have to

const motionController = new MotionController({
    target:pen,
    type:"pressmove",
    container:holder
});