Hi Gourav.
After downloading data from the server filters are rendered normally.
But then something is called and makes all cells filter row empty.
This code saves the day

let smartgrid = ...
virtualDataSource: function (resultCallbackFunction, details) {
   ...
   function refreshFilterPanel() {
      for (var i = 0; i < smartgrid.columns.length; i++) {
          smartgrid.columns[i]._filterEditorInitialized = false;
      };
      smartgrid._renderFrozenRows();
   }
   loadFromServer().then( (data) => {
      resultCallbackFunction({
         dataSource: data.items,
         virtualDataSourceLength: data.totalRecords
      });
      refreshFilterPanel();
      ....
    })
}

Best regards, Dmitry