Tween 'updateTo' only updates first child in a group

Phaser 3
1

I am trying to update the X and Y properties of a tween that I have created for a group of sprites. I am currently using the updateTo function to set a new value for each property that I want to update, in the update function.

function create ()
{
    var image1 = this.add.image(50, 100, 'block');
    var image2 = this.add.image(60, 200, 'block');
    var image3 = this.add.image(70, 300, 'block');

    tween = this.tweens.add({
        targets: [ image1, image2, image3 ],
        x: '+=600',
        y: '+=200',
        duration: 4000,
        ease: 'Power3'
    });
}

function update () {
    tween.updateTo('x', Phaser.Math.Between(200, 800));
}

However it seems that this only updates the X value for the very first box, the other two keep their original values.

Can updateTo be used for groups, or am I doing something wrong?

Thanks, Conor