OneWay CP issue

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

controllers.my-route.js

import Ember from 'ember';
import { oneWay, equal } from '@ember/object/computed';

export default Ember.Controller.extend({
  customRoutingType: oneWay('model.customRoutingType'),
  isFixedRouted: equal('customRoutingType', 'fixed').volatile().readOnly(),
  isDynamicRouted: equal('customRoutingType', 'dynamic').volatile().readOnly()
});

router.js

import EmberRouter from '@ember/routing/router';
import config from './config/environment';

const Router = EmberRouter.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
  this.route('my-route')
});

export default Router;

routes.my-route.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    return {
      customRoutingType: 'fixed'
    };
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

templates.my-route.hbs

{{#radio-button value='fixed' 
	radioClass='clickable' 
  groupValue=customRoutingType}}
	<span>Fixed</span>
{{/radio-button}}
{{#radio-button value='dynamic' 
	radioClass='clickable' 
  groupValue=customRoutingType}}
	<span>Dynamic</span>
{{/radio-button}}

<br/>
Custom Routing Type: {{customRoutingType}}<br/>
Fixed: {{isFixedRouted}}<br/>
Dynamic: {{isDynamicRouted}}

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "2.18.2",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-radio-button": "1.2.2"
  }
}