We have tested the scenario and managed to reproduce the same issue at our side. For the sake of correction, we have logged this problem in our issue tracking system as WORDSNET-22231. You will be notified via this forum thread once this issue is resolved. We apologize for your inconvenience.
We suggest you please use Aspose.PDF to convert PDF to HTML for better output. Following code example shows how to convert PDF to HTML using Aspose.PDF. Hope this helps you.
Aspose.Pdf.Document pdfDoc = new Aspose.Pdf.Document(MyDir + "Muster_Vertraulichkeitsvereinbarung.pdf");
pdfDoc.Save(MyDir + "output.html", Aspose.Pdf.SaveFormat.Html);