Insert batch didn't update the created_at field?

Did you include the created at field in the allowed fields?

Of course, I did. Same as in the documentaion.

PHP Code:

protected $useTimestamps = true;
protected $useSoftDeletes = true;
protected $createdField  = 'created_at';
protected $updatedField  = 'updated_at';
protected $deletedField  = 'deleted_at';