Modal not show selected values?

I have a form that looks like this, all variables are present when I DD all is OK in (screenshot 1) dd screen, all ok,

But the selected variables are not displayed in the modal window picture 2 Here (screenshot 2) Not showing selected in Modal, the Form:

@foreach ($products as $product)
{!! Form::model($products, [ 'method' => 'PATCH',  'route' => ['products.update', $product->id ], 'id' => 'frmProducts', 'name' => 'frmProducts','role'=>'form', 'novalidate' => '','class'=>'form-horizontal']) !!}

   <div class="form-group">
               <i class="fa fa-question-circle" aria-hidden="true" title="Vælg flere med ctrl tasten nede"></i>
           {!! Form::label('state_list', 'Vælg tilstande: ', ['class' => 'col-sm-4 control-label']) !!}
                 <div class="col-sm-7">
           {!! Form::select('state_list[]', $states, $product->state_list, ['class' => 'form-control', 'multiple' => true , 'id' => 'state_list', 'data-placeholder' => 'Vaelg en tilstand']) !!}
                 </div>
             </div> 

            {!! Form::close() !!}
  @endforeach

I think it is something with javascript? but do not know where to search for the error ??

var url = "/products";

$('.collapse').on('show.bs.collapse', function () {
    $('.collapse.in').collapse('hide');
});

    //display modal form for product editing todos
    $(document).on('click','.open_product_modal',function(){
        var product_id = $(this).val();

        $.get(url + '/' + product_id, function (data) {
            //success data formmater dato
            console.log(data);
            $('#product_id').val(data.id);
            $('#state_list').val(data.state_list);

            $('#visible').val(data.visible);
            $('#btn-save').val("update");
            $('#myModal').modal('show');
        })
    });
    //display modal form for creating new product
    $('#btn_add').click(function(){
        $('#btn-save').val("add");
        $('#frmProducts').trigger("reset");
        $('#myModal').modal('show');

    });
    //delete product and remove it from list
    $(document).on('click','.delete-product',function(){
        var product_id = $(this).val();
         $.ajaxSetup({
            headers: {
                'X-CSRF-TOKEN': $('meta[name="_token"]').attr('content')
            }
        })
        $.ajax({
            type: "DELETE",
            url: url + '/' + product_id,
            success: function (data) {
                console.log(data);
                $("#product" + product_id).remove();
            },
            error: function (data) {
                console.log('Error:', data);
            }
        });
    });
    //create new product / update existing product date
    $("#btn-save").click(function (e) {
        $.ajaxSetup({
            headers: {
                'X-CSRF-TOKEN': $('meta[name="_token"]').attr('content')
            }
        })
        e.preventDefault();
        var formData = {
            name: $('#name').val(),
            details: $('#details').val(),
            productgroup_id: $('#productgroup_id').val(),
            state_list: $('#state_list').val(),

        }
        //used to determine the http verb to use [add=POST], [update=PUT]
        var state = $('#btn-save').val();
        var type = "POST"; //for creating new resource
        var product_id = $('#product_id').val();;
        var my_url = url;
        if (state == "update"){
            type = "PUT"; //for updating existing resource
            my_url += '/' + product_id;
        }
        console.log(formData);
        $.ajax({
            type: type,
            url: my_url,
            data: formData,
            dataType: 'json',
            success: function (data) {
                console.log(data);
                var product = '<tr id="product' + data.id + '"><td>' + data.id + '</td><td>' + data.name + '</td><td>' + data.price + '</td><td>' + data.productunit + '</td><td>' + data.productgroup + '</td> <td>' + data.updated_at + '</td>';
                product += '<td><button class="btn btn-warning btn-detail open_product_modal" value="' + data.id + '"><i class="fa fa-pencil-square-o" title="Edit" aria-hidden="true"></i></button>';
                product += ' <button class="btn btn-danger btn-delete delete-product" value="' + data.id + '"><i class="fa fa-trash-o" title="Delete" aria-hidden="true"></i></button></td></tr>';
                if (state == "add"){ //if user added a new record dato formater
                    $('#products-list').append(product);
                }else{ //if user updated an existing record
                    $("#product" + product_id).replaceWith( product );
                }
                $('#frmProducts').trigger("reset");
                $('#myModal').modal('hide')
            },
            error: function (data) {
              console.log('Error:', data);
            {
                var errors = '';
                for(datos in data.responseJSON){
                    errors += data.responseJSON[datos] + '<br>';
                }
                $('#response').show().html(errors); //this is my div with messages
            }

            }
        });
    });

PLEASE Help :-)

via Chebli Mohamed