Data binding selected broken

[ToeFungi]

With the Polymer 2.0-preview, I have

<iron-swipeable-pages selected="{{selectedIndex}}"> attached to

selectedIndex: {
    type: Number,
    value: 0,
    observer: '_indexChanged'
}

In my function I check if the value is equal to 2 and then I set this.selectedIndex = 1 and this deselects everything and hides all the pages. Anyone know of a solution?