Relationship Reload Issue

adapters.application.js

import { Promise } from 'rsvp';

export default class AppAdapter {
  constructor(options) {
    Object.assign(this, options);
  }
  
  static create(options) {
    return new this(options);
  }
  
  findRecord() {
    return Promise.resolve({
      data: {
        type: 'person',
        id: '1',
        attributes: { name: 'Chris' },
        relationships: {
          father: {
            data: null,
            links: {
              related: './person/1/father/'
            }
          } 
        }
      }
    });
  }
  
  findBelongsTo() {
    return new Promise(resolve => {
      setTimeout(resolve, 3000);
    }).then(() => { return {
      data: {
        type: 'person',
        id: '2',
        attributes: { name: 'John' },
        /*
        relationships: {
          child: {
            data: {
              type: 'person', id: '1'
            }
          }
        }
        */
      }
    }});
  }
}

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  findUser() {
    let store = this.get('store');
    
    return store.findRecord('person', '1')
      .then(person => {
         this.set('user', person);
         let father = person.belongsTo('father').reload();
         return father;
      });
  },
  
  init() {
    this._super(...arguments);
    
		this.findUser();
  }
});

models.person.js

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

export default Model.extend({
  name: attr(),
  father: belongsTo('person', {
    async: false,
    inverse: 'child'
  }),

  child: belongsTo('person', {
  	async: false,
    inverse: 'father'
  }),
});

serializers.application.js

export default class MySerializer {
  constructor(options) {
    Object.assign(this, options);
  }
  
  static create(options) {
    return new this(options);
  }
  
  normalizeResponse(_, __, data) { return data; }
}

templates.application.hbs

<h1>Welcome to {{appName}}, {{user.name}}</h1>
My Id {{user.id}}.<br>My state is: <b>{{user.currentState.stateName}}</b>
<br>
{{user.father.name}} is your father. His ID is {{user.father.id}}.<br>His state is: <b>{{user.father.currentState.stateName}}</b>
<br>
{{outlet}}
<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": "3.8.0"
  }
}