We have an Ultrawebgrid inside ModalPopup Extender control in our application. In that ultrawebgrid we have one templeted column, in that we have checkboxes.  We are using client side sorting for that grid to sort data. If we sort any column, and then check some checkboxes and click Apply button to add the checked check boxes rows data into Database. But very first time after clicking on column header for sorting application is not recognizing the status of the checkboxes correctly, second time onwards it is working fine.

We are having the same in aspx page not in Modalpopexter, there it is working fine.