Multi graph import doesn't always work

[PulsarFox]

I'm using rdf-store-sparql, which communicates with a remote Jena triple store

When adding new quads to a dataset from two different graph, only the graph of the very first quad is impacted by the import request.

let quads =[];
quads.push(rdf.quad(subject, predicate, object, graph1));
quads.push(rdf.quad(subject, predicate, object, graph2));

let dataset = rdf.dataset(quads);
//Or even dataset.addAll(quads)

let stream = store.import(dataset.toStream());
rdf.waitFor(stream).then(() => { //doing something })

This lines of codes only adds quads on the first graph and not on the second.
The number of quads doesn't matter, I could have one quad going on the first graph and 20 going on the second, it will only add one quad to the store.