Element anchor property not updating unless I change the window size

I am trying to update the anchor property of an element in the update tick, and at first I thought it simply wasn’t working, but then I noticed that if I change the size of the window then it does update. But it only updates when the window is being resized, otherwise nothing happens.
I can see from logging to the console that the values are being updated correctly, they are just not shown until window resize. Is there something I need to/can manually call so that the update happens visually?

How are you updating the anchor? Can you share the code please?


MatteScreen.prototype.update = function(dt) {
        this.openAmount += dt * this.fadeSpeed;
        this.openAmount = pc.math.clamp(this.openAmount, 0, 0.5);
        this.topMatte.element.anchor.y = 0.5 + this.openAmount;
        this.bottomMatte.element.anchor.w = 0.5 - this.openAmount;
        if(this.openAmount >= 0.5){
            window.matteScreenOpen = false;