Thank you for contacting support.
We have been able to reproduce the issue with below code snippet in our environment. A ticket with ID PDFNET-45727 has been logged in our issue management system for further investigation and resolution. The ticket ID has been linked with this thread so that you will receive notification as soon as the ticket is resolved.
Document pdfDocument = new Document(dataDir + @"8308481_PDF Demo Document.pdf");
Aspose.Pdf.Forms.Form form = pdfDocument.Form;
var fields = form.Fields;
foreach (Aspose.Pdf.Forms.Field field in fields)
if (field.PartialName == "Form41559")
field.Value = "test string";
//field.Value = DateTime.Now.ToString("MM/dd/yyyy");
pdfDocument.Save(dataDir + "Filled_18.11.pdf");
We are sorry for the inconvenience.