Syncfunsio xslio exports null instead of blank in excel in C#

Question

I am using Syncfusion library to generate an excel report. I referred syncfusion to generate the report using template makers. The data is correctly exported in excel file but it is exporting NULL instead of blank string for some of nullable number columns. How can I write blank instead of NULL in excel for nullable fields.

Template file:

Output:

This is the code I am using.

using Syncfusion.XlsIO;

using (ExcelEngine excelEngine = new ExcelEngine())
{
    IApplication application = excelEngine.Excel;
    application.DefaultVersion = ExcelVersion.Excel2010;
    IWorkbook workbook = application.Workbooks.Open(_templateFilePath);
    IWorksheet worksheet = workbook.Worksheets[0];
    ITemplateMarkersProcessor marker = workbook.CreateTemplateMarkersProcessor();
    var data = _database.GetData();
    marker.AddVariable("DATA", data);
    marker.ApplyMarkers();
    workbook.SaveAs(_stReportFilePath);
    workbook.Close();
    excelEngine.Dispose();
}