Ember component's template issue with jQuery sortable

I'm trying to create a simple Ember component that wraps jQuery UI Sortable plugin. Unfortunately I have an issue with component's template when sortable is cancelled and model is updated manually. It looks like the DOM does not reflect the state of the model. I'm not able to find why.

I've created JS Bin to present this issue. When you change item position, the first one in the group should be removed. Unfortunately it works randomly.

What's wrong with this code?