selected data in multiple checkbox not recognized - cakephp-3.0

Question

I am getting frusted because the edit.ctp is not recognizing the stored data within a multible value checkbox. This is my code:
Controller:
public function edit($id = null) {
$this->set('userfunc', $this->Auth->user('userfunction_id'));
$user = $this->Users->get($id, [
'contain' => []
]);
if ($this->request->is(['patch', 'post', 'put'])) {
$user = $this->Users->patchEntity($user, $this->request->data);
if ($this->Users->save($user)) {
$this->Flash->success(__('The user has been saved.'));
return $this->redirect(['action' => 'index']);
} else {
$this->Flash->error(__('The user could not be saved. Please, try again.'));
}
}
**$selection = explode('#',$user->member);**
$userfunctions = $this->Users->Userfunctions->find('list', ['limit' => 200]);
$userappartments = $this->Users->Userappartments->find('list', ['limit' => 200]);
$userparkings = $this->Users->Userparkings->find('list', ['limit' => 200]);
$this->set(compact('user', 'userfunctions', 'userappartments', 'userparkings', 'selection'));
$this->set('_serialize', ['user']);
}
edit.ctp:
<?php
echo $this->Form->label('User.status', 'Status');
$options = $statusList;
echo $this->Form->radio('status', $statusList);
echo $this->Form->label('User.member', 'Mitglied');
echo $this->Form->input('member', ['options' => $memberList, 'multiple' => 'checkbox', 'label' => false, 'selected' => $selection]);
echo $this->Form->input('userappartment_id', ['options' => $userappartments, 'label' => 'Wohnung']);
echo $this->Form->input('userparking_id', ['options' => $userparkings, 'label' => 'Parkplatz']);
echo $this->Form->input('contact', ['label' => 'Kontakt']);
?>
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print_r is displaying an array that looks fine:
enter image description here
but the field in the form is emty:
enter image description here