I dont know where to write, but I will write here.
You have a bug in getting the single attribute from manufacturer attribute class
engine / Shopware / Bundle / StoreFrontBundle / Struct / Extendable.php :: 73
$manufacturer->getAttribute('someattribute') will return $this->attributes[$name] insted of $this->attributes['core']->get($name)
But until the bug is fixed, I found solution to use it like this: