Weird Attr Binding Issue

components.child-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  didUpdateAttrs() {
    alert('did receive attributes on child component')
  },
});

components.test-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  config: {},
  arbitraryString: 'peanut butter',
  anotherProperty: true,
  isReady: Ember.computed('config', 'anotherProperty', 'arbitraryString', function() {
    return !!(this.get('anotherProperty') && this.get('arbitraryString'))
  }),
  actions: {
    toggleDependentKey() {
      const config = this.get('config');
      const layers = Ember.get(config, 'layers');
      const targetLayerIndex = 0;
      const targetLayer = layers.objectAt(targetLayerIndex);
      Ember.set(targetLayer, 'layer',{ config: { color: 'purple' } });
    },
    
  },
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  weirdObject: {
    layers: [
      { 
        layer: {
          id: 'test',
          config: { 
            color: 'blue' 
          },
      	}
      },
      { 
        layer: {
          id: 'test2',
          config: { 
            color: 'green' 
          },
      	}
      }
    ]
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br/>
Each element in the below array is a component. That component's didUpdateAttrs never fires (although the template changes).
<br/>
<br/>
{{#test-component config=weirdObject as |api|}}
	<button onclick={{action api.toggleDependentKey}}>Change deeply nested array property</button>
{{/test-component}}
{{outlet}}
<br/>
<br/>

templates.components.child-component.hbs

{{layer.id}} - {{layer.config.color}}
{{yield}}

templates.components.test-component.hbs

'isReady' computed is {{isReady}}
<br/><br/>
Array that iterates:
{{#if isReady}}
	<ul>
  {{#each config.layers as |layer|}}
    <li>{{child-component layer=layer.layer}}</li>
  {{/each}}
  </ul>
{{/if}}
<br/>
{{yield (hash toggleDependentKey=(action 'toggleDependentKey'))}}

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}