Bad date sorting order in Pivot with date grouping

[cdokolas]

I have the following test code:

class PivotTest
{
	private static string PIVOT_WS_NAME = "Pivot";
	private static string DATA_WS_NAME = "Data";
	internal void RunTest()
	{
		using (ExcelPackage xlp = new ExcelPackage())
		{
			PrepareDoc(xlp);
			GenPivot(xlp);

			FileStream fs = File.Create("pivot.xlsx");
			xlp.SaveAs(fs);
			fs.Close();
		}
	}

	private void PrepareDoc(ExcelPackage xlp)
	{
		//generate date/value pairs for October 2017
		var series = Enumerable.Range(0, 31);
		var data = from x in series
				   select new { d = new DateTime(2017, 10, x + 1), x = x };
		//put data in table
		ExcelWorksheet ws = xlp.Workbook.Worksheets.Add(DATA_WS_NAME);
		int col = 1;
		ws.Cells[1, col++].Value = "Date";
		ws.Cells[1, col].Value = "Value";
		int row = 2;
		foreach (var line in data)
		{
			col = 1;
			ws.Cells[row, col++].Value = line.d;
			ws.Cells[row, col - 1].Style.Numberformat.Format = DateTimeFormatInfo.CurrentInfo.ShortDatePattern;
			ws.Cells[row, col].Value = line.x;
			row++;
		}
	}

	private void GenPivot(ExcelPackage xlp)
	{
		ExcelWorksheet ws = xlp.Workbook.Worksheets.Add(PIVOT_WS_NAME);
		ExcelWorksheet srcws = xlp.Workbook.Worksheets[DATA_WS_NAME];
		ExcelPivotTable piv = ws.PivotTables.Add(ws.Cells[1, 1], srcws.Cells[1, 1, 32, 2], "Pivot1");
		piv.DataFields.Add(piv.Fields["Value"]);
		ExcelPivotTableField dt = piv.RowFields.Add(piv.Fields["Date"]);
		dt.AddDateGrouping(eDateGroupBy.Days | eDateGroupBy.Months);
	}
}

When I open the pivot.xlsx file, I see the following (note that my system is setup with the Greek locale):

I un-zipped the xlsx file and the files seem all right; however, if I save the file from Excel without making any changes, the pivotTable1.xml file has the items in the pivotField in the wrong order. From that, I'm guessing that Excel messes-up the data when it reads the file.

[ramtejsudani]

Hi,
Can anyone let me know if this issue is resolved? Or is there any workaround for this issue?