Signature Name is not being persisted

.WithName(string signatureName)

var signer1 = (Email: "[email protected]",
                           Id: "signer-1",
                           FirstName: "David",
                           LastName: "NormalGmail",
                           Company: "ABC Company",
                           Title: "Software Developer");

            var doc = (Name: "Testing Doc",
                       Id: "DocId1");

            var anchor = (Text: "Please Sign",
                          Occurrence: 0,
                          Character: 0,
                          Width: 200,
                          Height: 50);

            PackageId packageId = null;
            using (var fs = File.OpenRead(@"test.pdf"))
            {
                var pkg = PackageBuilder.NewPackageNamed(doc.Name + " Package")
                              .WithSettings(DocumentPackageSettingsBuilder.NewDocumentPackageSettings())
                              .WithSigner(SignerBuilder
                                          .NewSignerWithEmail(signer1.Email)
                                          .WithCustomId(signer1.Id)
                                          .WithFirstName(signer1.FirstName)
                                          .WithLastName(signer1.LastName)
                                          .WithCompany(signer1.Company)
                                          .WithTitle(signer1.Title))
                              .WithDocument(DocumentBuilder
                                            .NewDocumentNamed(doc.Name)
                                            .FromStream(fs, DocumentType.PDF)
                                            .WithId(doc.Id)
                                            .WithSignature(SignatureBuilder.SignatureFor(signer1.Email)
                                                           .WithName("MySignatureName")
                                                           .WithPositionAnchor(TextAnchorBuilder.NewTextAnchor(anchor.Text)
                                                                               .AtPosition(TextAnchorPosition.TOPLEFT)
                                                                               .WithOccurrence(anchor.Occurrence)
                                                                               .WithCharacter(anchor.Character)
                                                                               .WithOffset(0, -anchor.Height)
                                                                               .WithSize(anchor.Width, anchor.Height)))).Build();

                packageId = eslClient.CreateAndSendPackage(pkg);

            }
            // dig into the below retreived variables. You'll see the signature name is null instead of "MySignatureName"
            var package = eslClient.GetPackage(packageId);
            var signatures = eslClient.ApprovalService.GetAllSignableSignatures(package, doc.Id, signer1.Id);