beforeModel issue

controllers.application.js

import Ember from 'ember';

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

routes.application.js

import Ember from 'ember';
const mixin1 = Ember.Mixin.create({
  beforeModel() {
    console.log('mixin1');
  	this._super(...arguments);
    
    return new Promise(resolve => {
    	setTimeout(() => {
        console.log('mixin1 resolved');
      	resolve();
      }, 1000);
    });
  }
})
const mixin2 = Ember.Mixin.create({
  beforeModel() {
    console.log('mixin2');
  	this._super(...arguments);
    return new Promise(resolve => {
    	setTimeout(() => {
        console.log('mixin2 resolved');
      	resolve();
      }, 500);
    });
  }
})
export default Ember.Route.extend(mixin1, mixin2, {
  beforeModel() {
    console.log('route');
    return this._super(...arguments);
  },
  model() {
  	console.log('hey, wait for mixins')
  }
});

templates.application.hbs

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

check console.
<br>
<br>

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": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}