GraphQL filter on second relationship not working (one to many to one)

I defined product, contributions and actors (a collection for each). A product has contributions (list of ObjectID) and a contribution has an actor [and a product] (objectID reference). When I want all products with contributions with actors with a certain name or postcode, it doesn’t work. The name or postcode filter is not applied.

The query :

query {
  product_contributions(query: { actor: { name: "test"} } ) {
    product{
      name
    }
    actor {
      name
    }
  }
  products(query: { contributions: { actor : { name: "test" } } }) {
    name
    contributions {
      actor {
        name
      }
    }
  }
}

gives

{
  "data": {
    "product_contributions": [],
    "products": [
      {
        "contributions": [
          {
            "actor": {
              "name": "Coopérative Pur Ardenne"
            }
          }
        ],
        "name": "Lait de Pâturage demi-écrémé"
      }
    ]
  }
}

Both should be empty …

Defined relationship for product :

{
  "contributions": {
    "foreign_key": "_id",
    "ref": "#/relationship/mongodb-atlas/digicirco/product_contributions",
    "is_list": true
  }
}

Defined relationships for product_contributions :

{
  "actor": {
    "ref": "#/relationship/mongodb-atlas/digicirco/actors",
    "foreign_key": "_id",
    "is_list": false
  },
  "product": {
    "ref": "#/relationship/mongodb-atlas/digicirco/products",
    "foreign_key": "_id",
    "is_list": false
  }
}