GridLookup - The client-side ValueChanged event is not raised when changing a value via keyboard without opening the dropdown

I use a GridLookup instead of an Combobox. I do this because old inative products should no longer be selected by the user.
The control GridLookup works well, but if I change the value using the keyboard arrows then the Event ValueChanged is only triggerd when the grid view dialog is open. If the grid view dialog is closed and i use keyboard arrows to change the value then the value is indeed changed, but the event ValueChanged is not triggered.

File _GridLookupProduktartPartial.cshtml:

@using Bytergy.App_Code
@model Bytergy.Models.LoanPreCalculation.Vorkalkulation

var gridLookup = Html.DevExpress().GridLookup(s => {
ControlsHelper.DefaultSettings(s);
s.Name = "SelProduktartID";
s.KeyFieldName = "ID";
s.Width = 300;
s.GridViewProperties.CallbackRouteValues = new { Controller = "LoanPreCalculation", Action = "GridLookupProduktartPartial"};
s.Properties.SelectionMode = GridLookupSelectionMode.Single;
s.Properties.TextFormatString = "{0}";
s.GridViewProperties.Settings.ShowGroupPanel = false;
s.GridViewProperties.Settings.ShowFilterRow = false;
s.GridViewProperties.Settings.ShowColumnHeaders = true;
s.GridViewProperties.SettingsPager.Mode = GridViewPagerMode.ShowAllRecords;
s.GridViewProperties.SettingsBehavior.EnableRowHotTrack = true;
s.Properties.ClientSideEvents.ValueChanged = "OnChangedProduktartID";
s.Properties.ClientSideEvents.Init = "OnInitProduktartID";
s.Properties.ClearButton.DisplayMode = ClearButtonDisplayMode.OnHover;
s.Columns.Add(c =>
{
c.FieldName = "Name";
c.Caption = "Text";
c.Width = Unit.Pixel(300);
});
s.Columns.Add(c =>
{
c.FieldName = "KoreID";
c.Caption = "KoreID";
c.Width = Unit.Pixel(90);
});
s.Columns.Add(c =>
{
c.FieldName = "ID";
c.Caption = "Schlüssel";
c.Width = Unit.Pixel(55);
});
s.Columns.Add(c =>
{
c.FieldName = "Aktiv";
c.Caption = "Aktiv";
// c.Visible = true;
// c.Width = Unit.Pixel(55);
});
s.Columns.Add(c =>
{
c.FieldName = "IsKontokorrent";
c.Caption = "IsKontokorrent";
// c.Visible = true;
// c.Width = Unit.Pixel(55);
});
s.DataBound = (sender, e) =>
{
var gLookup = (MVCxGridLookup)sender;
gLookup.GridView.Width = 300;
gLookup.GridView.Settings.VerticalScrollBarMode = ScrollBarMode.Visible;
gLookup.GridView.Settings.VerticalScrollableHeight = 300;
};
s.GridViewProperties.BeforeGetCallbackResult = (sender, e) =>
{
var grid = (ASPxGridView)sender;
if (grid.VisibleRowCount <= 2)
grid.Settings.VerticalScrollBarMode = ScrollBarMode.Hidden;
};
s.GridViewProperties.HtmlRowCreated = (sender, e) =>
{
var valAktive = e.GetValue("Aktiv");
if (valAktive != null) {
bool aktiv = (bool)(e.GetValue("Aktiv"));
e.Row.Visible = aktiv;
}
else {
e.Row.Visible = true;
}
};
});
}
@gridLookup.BindList(ViewBag.ListProduktart).Bind(Model.ProduktartID).GetHtml()

File EditPage.cshtml:
…

<scripttype="text/javascript">
function OnInitProduktartID(s, e) {
SetVisibilityProduktartID(s);
}
function OnChangedProduktartID(s, e) {
SetVisibilityProduktartID(s);
}
function SetVisibilityProduktartID(s) {
var myVal = s.GetValue();
console.log("Produktart changed to name: " + myVal);
}
</script>
@Html.DevExpress().FormLayout(settings =>
{
 …
groupItem.Items.Add(i =>
{
ControlsHelper.DefaultSettings(i);
i.Caption = "Produktart";
i.SetNestedContent(() =>
{
Html.RenderAction("GridLookupProduktartPartial", new { model = Model });
});
});
…