ArgumentOutOfRangeException is thrown while saving DOCX to PDF using .NET

Hi all, i got this err when saving the docx document to pdf format. Any one can help me?
Also, i see the page count of the document is different per debug time.
My file
10MB.zip (8.3 MB)

My code:
var document = new Aspose.Words.Document(assetPath);
var PageCount = document.PageCount;

var memoryStream = new MemoryStream();
var pdfSaveOptions = new Aspose.Words.Saving.PdfSaveOptions(){PageCount = 100 /*save first 100 pages*/};
document.Save(memoryStream,  pdfSaveOptions);

Exception:

System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values. (Parameter ‘pageCount’)

System.ArgumentOutOfRangeException
Specified argument was out of the range of valid values. (Parameter ‘pageCount’)
at Aspose.Words.Document. (Int32 , Int32 )
at ​ ( , ​ )
at ​ . ​( )
at . ​( )
at Aspose.Words.Document. ( )
at Aspose.Words.Document.​(Stream , String , SaveOptions )
at Aspose.Words.Document.Save(Stream stream, SaveOptions saveOptions)

@newsky1006

We have tested the scenario using the latest version of Aspose.Words for .NET 20.9 and have not found the shared issue. So, please use Aspose.Words for .NET 20.9.