Commented Issue: Saving workbook creates extra NumFmt elements [8369]

It appears that each time a workbook is saved a empty NumFmt (NumberingFormat) element is appended in the stylesheet. Once this is done enough times, it will start stepping on the built-in formats. I was noticing this with the percent format which I belive is #10.

The excel file attached has one cell, formatted as a percentage. After 9 saves, the formatting is lost.
In my practical application the stream was being passed around and many classes were opening a workbook from the stream and saving back to the stream.

This was the latest version, 77207



byte[] calculatedExcelStreamBytes = File.ReadAllBytes("c:\\LoseFormatTest.xlsx");

using (MemoryStream calculatedExcelStream = new MemoryStream())
{
calculatedExcelStream.Write(calculatedExcelStreamBytes, 0, calculatedExcelStreamBytes.Length);
XLWorkbook b = new XLWorkbook(calculatedExcelStream);

b.Save(); // Each save will increase the number of formats written, looking to step on built-in formats
b.Save();
b.Save();
b.Save();
b.Save();
b.Save();
b.Save();
b.Save();
b.Save(); // At this point we are stepping on the percent format
b.Save();
b.Save();
b.Save();
b.Save();

using (FileStream fs = new FileStream("C:\\LoseFormatTest.Modify.xlsx", FileMode.Create, FileAccess.Write))
{
calculatedExcelStream.WriteTo(fs);
fs.Flush();
fs.Close();
}
}
Comments: ** Comment from web user: FeelingPhoggy **

I am having the same issue, as far as I can tell.

I have a workbook with multiple worksheets. When make changes to 1 worksheet and then save the workbook, date formatting on a completely different worksheet than I edited is lost and the dates do not appear as they did before the .Save() operation.

Any help or tips for workarounds would be great.