unload Issue

adapters.post.js

import DS from 'ember-data';

export default DS.RESTAdapter.extend({
  host: 'https://jsonplaceholder.typicode.com'
});

controllers.application.js

import Ember from 'ember';

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

models.post.js

import Model from 'ember-data/model';
import attr from 'ember-data/attr';
import { belongsTo, hasMany } from 'ember-data/relationships';

export default Model.extend({
  "userId": attr(''),
  "title":  attr(''),
  "body":  attr('')
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  async model() {
  	this._super(...arguments);
    await this.store.findRecord('post', 1)
    await this.store.unloadAll();
  
		this.store.peekAll('post')
  
    await this.store.findRecord('post', 1);
    await this.store.findRecord('post', 2);

    await this.store.unloadAll('post');
    
    return this.store.peekAll('post');
  }
});

serializers.post.js

import DS from 'ember-data';

export default DS.RESTSerializer.extend({
  normalizeSingleResponse(store, primaryModelClass, payload, id, requestType) {
    payload = {
    	post: payload
    };
    
    return this._super(store, primaryModelClass, payload, id, requestType);
  }
});

templates.application.hbs

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

{{#each model as |m| }} 
	title: {{m.title}} <br>
{{/each}}
<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"
  }
}