How to change transform.y of a Rectangle object with pinned to the bottom in Spark AR Studio?

Question

I want to change the position of a Rectangle object (rectangle0) with pinning to the bottom and right. But I couldn't change the y-position of it when it is pinned to the bottom. It works fine with it pinned to the top.

Also I couldn't change the x-position when it is pinned to the right. It works fine with it pinned to the left.

Any ideas would be appreciate.

rectangle with pinning to the bottom

var timer = Time.setInterval(update, 10);
function update() {
    if(scale < 1.0)
    {
        scale += 0.01;
    }
    rect.transform.scaleX = scale;
    rect.transform.scaleY = scale;
    rect.transform.x = rect_posx - rect_width * 0.5 * (1.0 - scale);
    rect.transform.y = rect_posy + rect_height * 0.5 * (1.0 - scale);
}