Hello Agraj,

Thank you for the provided resources.

Please take some time to go through the ComboBox virtualization article, more specifically the Configuration section. It shows the minimum configurations required for the virtualization to work properly. You will see that there is a formula to calculate the pageSize, based on the itemHeight and height configurations of the widget:

height: 520,
dataSource: {
    pageSize: 80,
    serverPaging: true,
    serverFiltering: true
    type: "odata",
    transport: {
        read: "https://demos.telerik.com/kendo-ui/service/Northwind.svc/Orders"
    },
              

If you look follow this link to the modified version of the provided Dojo, you will see that the correct result will be returned.

I hope I was helpful. Feel free to contact us if you have further questions.

Regards,
Martin
Progress Telerik