ember-simple-auth: Session service not instantiated in Fastboot

I have just upgraded to master and started integrating ember-simple-auth with fastboot, switching to Cookie session store from Adaptive as instructed.

However the session’s state doesn’t seem to be instantiated on the server. While ember_simple_auth-session cookie is present with all the necessary data, the session.isAuthenticated still returns false and session.data is empty in fastboot mode:

// /app/routes/application.js
import Ember from 'ember';
import ApplicationRouteMixin from 'ember-simple-auth/mixins/application-route-mixin';

export default Ember.Route.extend(ApplicationRouteMixin, {
  currentUser: Ember.inject.service(),
  fastboot: Ember.inject.service(),

  beforeModel() {
    // Cookie is present:
    Ember.Logger.log('cookies', this.get('fastboot.request.cookies'));
    // => { 'ember_simple_auth-session': '{"authenticated":{"authenticator":"authenticator:devise","token":"XhIJ...","email":"...@...com"}}' }

    // But session is not restored from cookie:
    Ember.Logger.log('session.data', this.get('session.data'));
    // => { authenticated: {} } {}
    Ember.Logger.log('session.isAuthenticated', this.get('session.isAuthenticated'));
    // => false

    return this._loadCurrentUser();
  },
  _loadCurrentUser() { return this.get('currentUser').load(); },
  sessionAuthenticated() {
    this._loadCurrentUser().then(() => {
      if (this.get('session.data.redirectUrl')) {
        var redirectUrl = this.get('session.data.redirectUrl');
        this.get('session').set('data.redirectUrl', null);
        window.location.replace(redirectUrl);
      }
    }).catch(() => this.get('session').invalidate() );
  },
});

On the frontend the same code works as expected returning true for session.isAuthenticated and restoring session.data from cookie.

Not sure if I’m doing something wrong, or if this is a bug.