I'm trying to export a report to Excel using FastReport in my ASP.NET Core application. However, when I generate the Excel file, all the data appears in a single column rather than being properly split into multiple columns.

Below is my current code:

 public class DosyaOlusturService : IDosyaOlusturService {


 public byte[] DosyaOlustur(string html, ReportsParametersVm reportsParametersVm, string path)
 {
     string filePath = path + reportsParametersVm.OutputFileName; // Dosya yolu

     if (reportsParametersVm.ButtonName == "PDF")
     {
         try
         {
             var htmlToPdf = new HtmlToPdfConverter
             {

                 CustomWkHtmlArgs = "--dpi 300 --enable-local-file-access --disable-smart-shrinking --zoom 0.6",
                 PageWidth = 210,
                 PageHeight = 297,
                 Margins = new PageMargins { Top = 5, Bottom = 5, Left = 2, Right = 2 },
                 Orientation = reportsParametersVm.PdfLandscape == true ? PageOrientation.Landscape : PageOrientation.Portrait,

             };
             var pdfBytes = htmlToPdf.GeneratePdf(html);

             File.WriteAllBytes(filePath, pdfBytes);

             return pdfBytes;
         }
         catch (Exception)
         {
             return new byte[0];
         }
     }
     else
     {
         try
         {
             // Dosyayı oluştur ve yazma modunda aç
             using (StreamWriter writer = new StreamWriter(filePath))
             {
                 writer.WriteLine(html);
             }

             // Oluşturulan dosyayı oku
             byte[] fileBytes = File.ReadAllBytes(filePath);
             return fileBytes;
             //return File(fileBytes, "application/octet-stream", fileName);

         }
         catch (Exception ex)
         {
             return new byte[0];
             //Console.WriteLine($"Hata oluştu: {ex.Message}");
         }
     }

 }

 public RaporOlusturResponse FastReportRaporOlusturPDF(DataTable dataTable, ReportsParametersVm reportsParametersVm, bool isSendFromMail)
 {


     Report report = new Report();


     FastReport.Utils.Config.WebMode = true;


     string reportPath = Path.Combine(Directory.GetCurrentDirectory(), $"Views\\Reports\\FastReports\\Rpr_{reportsParametersVm.Code}.frx");

     report.Load(reportPath);

     string viewName = $"vw_{reportsParametersVm.Code}";
     report.RegisterData(dataTable, viewName);

     using MemoryStream ms = new();
     PDFSimpleExport pdfExport = new PDFSimpleExport();

     string outputPath = isSendFromMail ? Path.Combine(Directory.GetCurrentDirectory(), $"Content\\MailAttachments\\{reportsParametersVm.OutputFileName}") :
         Path.Combine(Directory.GetCurrentDirectory(), $"Content\\CreatedReports\\{reportsParametersVm.OutputFileName}");

     try
     {
         report.Prepare();
     }
     catch (Exception ex)
     {
         Console.WriteLine($"Prepare Hatası: {ex.Message}");
     }

     try
     {
         report.Prepare();
         report.Export(pdfExport, ms);
     }
     catch (Exception ex)
     {
         Console.WriteLine($"Export Hatası: {ex.Message}");
     }

     ms.Position = 0;

     var fileBytes = ms.ToArray();

     // PDF dosyasını diske kaydet

     System.IO.File.WriteAllBytes(outputPath, fileBytes);

     return new RaporOlusturResponse()
     {
         File = new FileModel()
         {
             FileBytes = isSendFromMail ? fileBytes : null,
             MimeType = reportsParametersVm.ReportMimeType,
             OutputFileName = reportsParametersVm.OutputFileName,
             OutputFilePath = outputPath,
         },
         Message = "Başarılı",
         IsSucces = true
     };
 }



 public RaporOlusturResponse FastReportRaporOlusturEXCEL(DataTable dataTable, ReportsParametersVm reportsParametersVm, bool isSendFromMail)
 {
     Report report = new Report();
     FastReport.Utils.Config.WebMode = true;

     string reportPath = Path.Combine(Directory.GetCurrentDirectory(), $"Views\\Reports\\FastReports\\Rpr_{reportsParametersVm.Code}.frx");
     report.Load(reportPath);

     string viewName = $"vw_{reportsParametersVm.Code}";

     // Create a DataSet and add the DataTable to it
     DataSet dataSet = new DataSet();
     dataTable.TableName = viewName;
     dataSet.Tables.Add(dataTable);

     // Register the DataSet
     report.RegisterData(dataSet, viewName, true);

     // Update the dictionary to reflect the data source
     report.Dictionary.DataSources.Clear();
     report.Dictionary.RegisterData(dataSet, viewName, true);

     using MemoryStream ms = new();
     HTMLExport htmlExport = new HTMLExport();

     string outputPath = isSendFromMail ? Path.Combine(Directory.GetCurrentDirectory(), $"Content\\MailAttachments\\{reportsParametersVm.OutputFileName}") :
                                          Path.Combine(Directory.GetCurrentDirectory(), $"Content\\CreatedReports\\{reportsParametersVm.OutputFileName}");

     try
     {
         report.Prepare();
     }
     catch (Exception ex)
     {
         Console.WriteLine($"Prepare Error: {ex.Message}");
     }

     try
     {
         report.Export(htmlExport, ms);
         DosyaOlustur(htmlExport.ToString(), reportsParametersVm, outputPath);
     }
     catch (Exception ex)
     {
         Console.WriteLine($"Export Error: {ex.Message}");
     }

     ms.Position = 0;
     var fileBytes = ms.ToArray();

     File.WriteAllBytes(outputPath, fileBytes);

     return new RaporOlusturResponse()
     {
         File = new FileModel()
         {
             FileBytes = isSendFromMail ? fileBytes : null,
             MimeType = reportsParametersVm.ReportMimeType,
             OutputFileName = reportsParametersVm.OutputFileName,
             OutputFilePath = outputPath,
         },
         Message = "Success",
         IsSucces = true
     };
 }}

I want the generated Excel file to properly display the data in separate columns. But it seem like below;

The DataTable has multiple columns, but the Excel file places all the data into one column.

What am I missing in the configuration or export process? How can I fix this to make the exported Excel file properly structured?

Any help or guidance would be greatly appreciated!