Thanks for contacting support.
I have tested the scenario by converting one of my sample PDFs into XLS format with Aspose.Pdf for .NET 17.4.0 and was unable to notice any issue. You can check following code snippet which I have used.
Document doc = new Document(dataDir + “SamplePdf.pdf”);<o:p></o:p>
ExcelSaveOptions options = new ExcelSaveOptions();
+ "SampleExcel.xls", options);
Please note that sometimes issue is related with specific input document and to observe the same issue in our environment, we need that file. We will really appreciate if you please share an input document along with code snippet which you are using for conversion, so that we can try to replicate the issue in our environment and address it accordingly.