Not-Highlight text become highlight using Aspose.words

Hi,
We have a problem with highlight text using Aspose.words.
In out application we use Aspose library to sign a document (replace the @SIGNATURE@ with signature image) and save the document to proper format after signed. We found that if text was highlighted in the document and then changed to not-highlight, after signed, the not-highlight text became highlight again.
The attached c# problem is the code we use to sign the document (the sign method).
can you pleaes take a look and let us know if there is any solution?
Thanks,
Andy

Hi
Thanks for your request. Most likely this is known issue #5483 in our defect database. This issue was fixed few releases ago. So please upgrade to the latest version, you can download it from here:
https://releases.aspose.com/words/net
Also please attach your document for testing and tell which version of Aspose.Words you are using.
Best regards.