Ember.Select doesn't initiate list according to 'selectionBinding'

I have many to many relationship between books and their authors. Every book has a collection of associated authors (and vice versa). On book's edit page I am displaying a multiple selection, but the problem is that the selection doesn't show authors associated with the book I am currently editing, instead there is just a list with no selected options. Then I can select authors and it's working just alright, it's just that the initial state of 'select' component gets erased (it also clears the collection of authors. If I enter the edit page and navigate to somewhere else without selecting any authors suddenly book that had a few authors doesn't have any of them anymore).

Here is the select snippet from template:

{{view "select" class="form-control" 
                multiple=true 
                contentBinding="allAuthors" 
                optionLabelPath="content.fullName" 
                optionValuePath="content.id" 
                selectionBinding="model.authors"}}

All authors are put into the controller at route's setupController hook, like this:

App.BookEditRoute = Ember.Route.extend({
    setupController: function(controller, model) {
        controller.set('model', model);
        controller.set('allAuthors', this.store.find('author'))
    }
})

And obviously controller's model has authors property inherited from parent controller.