onesignal: Chrome Big Picture not work

Hi,

I need to set an large image as attachment for my notifications, but it doesn’t work. This is my sample code:

public function toOneSignal($notifiable)
{
    return OneSignalMessage::create()
        ->setIcon($this->site_logo)
        ->setImageAttachments($this->post->featured_image)
        ->setSubject($this->post->title)
        ->setBody($this->post->getExcerpt(120))
        ->setUrl($this->post->canonical_link)
        ->setButton(
            OneSignalButton::create('id') ->text('Download')
        );
}

Please help me solve this. Any help would be appreciated! Thanks