Aggregates seem to be not implemented

[larisa1995]

For example

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix ex: <http://www.example.com/> .
@prefix jj: <http://ontology.yy.org/xx/jj#> .
@prefix grel: <http://users.ugent.be/~bjdmeest/function/grel.ttl#> .
@prefix ff: <http://ontology.yy.org/xx/ff#> .

ex:ne_1 rdf:type jj:Entity ;
	skos:notation "ne_1" .

ex:ne_2 rdf:type jj:Entity ;
	skos:notation "ne_2" .

ex:ne_3 rdf:type jj:Entity ;
	skos:notation "ne_3" .

ex:qq_1 ff:hasElementCollectionUnordered ex:qq_1_uoc1 ;
	rdf:type jj:Entity ;
	skos:notation "qq_1" .

ex:qq_1_uoc1 ff:hasElementPart ex:ne_1, ex:ne_2 ;
	rdf:type ff:ff_UnorderedCollection ;
	skos:notation "qq_1_uoc1" .

ex:qq_2 ff:hasElementCollectionUnordered ex:qq_2_uoc1 ;
	rdf:type jj:Entity ;
	skos:notation "qq_2" .

ex:qq_2_uoc1 ff:hasElementPart ex:ne_2, ex:ne_3 ;
	rdf:type ff:ff_UnorderedCollection ;
	skos:notation "qq_2_uoc1" .

and query

prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix xsd: <http://www.w3.org/2001/XMLSchema#>
prefix sd: <http://www.w3.org/ns/sparql-service-description#>
prefix ex: <http://www.example.com/>
prefix ff: <http://ontology.yy.org/xx/ff#> 
prefix grel: <http://users.ugent.be/~bjdmeest/function/grel.ttl#>
prefix skos: <http://www.w3.org/2004/02/skos/core#>
prefix ex: <http://www.example.com/>

SELECT ?nePartName (count(distinct ?ne) as ?count)
WHERE
{
	?nePart ^ff:hasElementPart/^ff:hasElementCollectionUnordered ?ne ; skos:notation ?nePartName .
	
} 
GROUP BY ?nePartName
HAVING (?count > 1)
LIMIT 5

I get in apache-jena\bat\sparql.bat result

nePartName,count
ne_2,2

In https://atomgraph.github.io/SPARQL-Playground/ I get empty table.