get-not-working

controllers.application.js

import Controller from '@ember/controller';
import { get, set } from '@ember/object';
import { action, computed } from '@ember-decorators/object';

export default class ApplicationController extends Controller {
  init() {
    super.init(...arguments);
    
    const initial = [
      { emailAddress: 'hello@example.com' },
      { emailAddress: 'goodbye@example.com' },
    ];
    
    const selected = initial
      .reduce((dict, { emailAddress }) => Object.assign({}, dict, { [emailAddress]: false }), {});
    
    this.setProperties({ initial, selected });
  }
  
  @action
  toggleAll() {
    const updated = Object.entries(this.selected)
      .reduce((dict, [k, v]) => Object.assign({}, dict, { [k]: !v }), {});
    set(this, 'selected', updated);
  }
   
  @computed('selected')
  get selectedAsString() {
    return Object.entries(this.selected)
      .reduce((dict, [k, v]) => Object.assign({}, dict, { [k]: `${v}` }), {});
  }
}

templates.application.hbs

<ul>
  {{#each this.initial as |item|}}
  	{{log this.selected}}
    {{log item.emailAddress}}
    {{log (get this.selected item.emailAddress)}}
    {{log (get this.selectedAsString item.emailAddress)}}

		<li>
      {{item.emailAddress}} is
      {{if (get this.selected item.emailAddress) 'selected' 'not selected'}}.<br>
      Literal value: {{get this.selectedAsString item.emailAddress}}
    </li>
  {{/each}}
</ul>

<button onclick={{action this.toggleAll}}>Toggle!</button>

twiddle.json

{
  "version": "0.15.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.2.2",
    "ember-template-compiler": "3.2.2",
    "ember-testing": "3.2.2"
  },
  "addons": {
    "ember-data": "3.2.0",
    "ember-decorators": "2.4.1"
  }
}