Using ember.js, why is my sorting not working?

I have a model called discussions, that I'm trying to sort by ID. I'm trying to display this sorted list of discussions in 2 places in my app, firstly at '/discussions' where the list sorts as I would expect, and secondly as a module on another page, '/syndicates/0/activity', where the list sorting does not work.

I'm defining the sort in my DiscussionsController

App.DiscussionsController = Ember.ArrayController.extend
  sortProperties: ['id'],
  sortAscending: true
  isThisControllerBeingCalled: true

which should be called by default at '/discussions'. Here's the route:

App.DiscussionsRoute = Em.Route.extend
  model: ->
    @store.find 'discussion'
  renderTemplate: ->
    @render 'discussions',
      into: 'application',
      outlet: 'full'

for the discussions module at '/syndicates/0/activity' I'm pulling in the discussions via setupController with a controllerFor:

App.SyndicatesRoute = Em.Route.extend(
  controllerName: 'discussions'
  model: ->
    @store.find 'syndicate'
  renderTemplate: ->
    @render 'syndicates',
      into: 'application',
      outlet: 'syndicates'
    @render 'discussion_module',
      into: 'application',
      outlet: 'left',
      controller: 'discussions'
  setupController: (controller, model) ->
    @controllerFor('discussions').set('discussions_for_module', @store.find 'discussion')
)

For '/syndicates/0/activity' the discussions remain unsorted. I tried to confirm that the discussions controller was being called sucessfully by setting a property in the controller, which I could see in both places.

Any idea why the discussions are not being sorted?