Why is the flatmap-operator not working as I understood it?

Question

fetch(url) returns a promise, which I'm converting to observable using flatmap. Why is this not working?

Rx.Observable
    .from(imgSrc)
    .map(url => fetch(url))
    .flatmap( res => R.Observable.fromPromise(res))
    .subscribe(
        function(res) {
                        console.log(res);
                    },
                    function(err){
                        console.log("Errorororrororororor:"+JSON.stringify(err));
                        response.status(500).send(
                                        {
                                            "error":err
                                        });
                    },
                    function(){
                        console.log("completed promise!!")
                        response.status(200).send(
                                        {"data": [{
                                               "id": "testing id",
                                               "url": "https://test.com/1.jpg"
                                           }]
                                        });
                    }
    );