To reproduce:
- Use the details view and add some columns.
- Hide the first column and export the data.
- The header row still contains the hidden column and the data is not exported.

Workaround:
Remove the first header cell manually:

private void Renderer_WorkbookCreated(object sender, WorkbookCreatedEventArgs e)
{
    var sheet = e.Workbook.Worksheets[0] as Worksheet;
    CellIndex range = new CellIndex(0, 0);
    CellSelection selection = sheet.Cells[range];


    selection.Remove(RemoveShiftType.Left);

}