Uploading images using Form Collections and Doctrine in Symfony2
When you add by_reference => false you are suposed to set the counter entity in the add function.
So your property_id should be persisting correctly in the image changing the addImage function in your propery to:
public function addImage(\Mata\MainBundle\Entity\Image $image){ $this->images[] = $image; $image->setProperty($this); return $this;}