Update a HasMany records - cakephp-3.0

Question

I am converting a working app from cakephp2 to cakephp3. I'm struggling to get a form that updates hasMany records to work.
The app has the following structure:
MODELS:
use Cake\ORM\Table;
use Cake\Validation\Validator;
class AwardsTable extends Table
{
public function initialize(array $config)
{
$this->hasMany('Levels', ['sort' => 'sort_order']);
}
}
namespace App\Model\Entity;
use Cake\Auth\DefaultPasswordHasher;
use Cake\ORM\Entity;
class Award extends Entity
{
protected $_accessible = [
'name' => true,
'url' => true,
'organisation' => true,
'detail' => true,
'logo' => true,
'levels' => true,
'Levels' => true
];
}
IN THE FORM:
<?= $this->Form->input("levels.$i.name", 'label'=>false,'type'=>'text','value' => $award->name]);?>
<?= $this->Form->input("levels.$i.id", ['value' => $award->id]); ?>
CONTROLLER
$this->Awards->patchEntity($award, $this->request->data, ['associated' => ['Levels']]);
if ($this->Awards->save($award)) {
$this->Flash->success(__('Your Award has been saved.'));
$this->redirect(['action' => 'index']);
}
This seems inline with what is recommended here: http://book.cakephp.org/3.0/en/views/helpers/form.html#associated-form-inputs
I've tried a few variations with capitalisation & pluralisation. The award data saves correctly but the associated levels data does not save.
What am I missing to get the has_many association data to save?
EDIT: Example Data array submitted:
2016-01-28 23:32:56 Error: Array
(
[id] => 4
[name] => test award
[organisation] => test org
[url] => http://www.example.com
[detail] =>
[levels] => Array
(
[0] => Array
(
[name] => test 1
[id] => 4
)
[11] => Array
(
[name] => test
[id] => 16
)
)
[image] => Array
(
[name] =>
[type] =>
[tmp_name] =>
[error] => 4
[size] => 0
)
)

Answer 1

In LevelEntity verify if 'id' is accessible
protected $_accessible = [
'*' => true,
'id' => true,
];