Thanks for your posting and using Aspose.Cells.
Please download and use the latest version: Aspose.Cells
for .NET v188.8.131.52 it works fine.
I have tested this issue with the following code and it generated correct output excel file which I have attached for your reference.
string filePath = @“F:\Shak-Data-RW\Downloads\TFS11661.xlsx”;
Workbook workbook = new Workbook(filePath);
workbook.Save(filePath + “.out.xlsx”);
Thanks - this does indeed now work.