TYPO3.Flow

If a persistent object is contained in an array property, the serialization failes. It won't detect the object as persistent but will persist it as if it was a simple data object. This will be broken as soon as the session is resumed/ the object serializer is unserializing this data stream.

The reason is that persistent object detection is only present in method serializeObjectAsPropertyArray. Method buildStorageArrayForArrayProperty only contains a small is_object that won't respect the persistence:

if (is_object($value)) {
                $storableArray[$key][self::TYPE] = 'object';
                $storableArray[$key][self::VALUE] = spl_object_hash($value);

                $this->serializeObjectAsPropertyArray($value, FALSE);
            }