Converting RTF file with images to TIFF

Question

I got my .rtf file I generated using MSWord, and I added some images to it, it has 28000 lines, and now I'm trying to convert that rtf file to tiff image. Here's the code I have:

 static void ConvertRtfToTiff(string rtfFilePath, string outputDirectory)
 {
     // Create output directory if it doesn't exist
     if (!Directory.Exists(outputDirectory))
     {
         Directory.CreateDirectory(outputDirectory);
     }

     // Load RTF content using FileStream and StreamReader
     string rtfContent;
     using (FileStream fs = new FileStream(rtfFilePath, FileMode.Open))
     {
         using (StreamReader reader = new StreamReader(fs))
         {
             rtfContent = reader.ReadToEnd();
         }
     }

     // Create a RichTextBox control to load the RTF content
     using (RichTextBox richTextBox = new RichTextBox())
     {
         // Set the size of the RichTextBox
         int width = (int)(8.27 * 100); // A4 width in pixels (assuming 100 DPI)
         int height = (int)(11.69 * 100); // A4 height in pixels (assuming 100 DPI)
         richTextBox.Size = new Size(width, height);
         richTextBox.Multiline = true;
         richTextBox.ReadOnly = true;

         // Assign RTF content to the RichTextBox
         richTextBox.Rtf = rtfContent;

         // Iterate through the RTF content and extract images
         int imageCount = 0;
         foreach (var image in GetImagesFromRtf(richTextBox))
         {
             string imagePath = Path.Combine(outputDirectory, $"image_{imageCount}.tiff");

             // Delete the output file if it already exists
             if (File.Exists(imagePath))
             {
                 File.Delete(imagePath);
             }

             // Save the image as TIFF format
             image.Save(imagePath, ImageFormat.Tiff);

             Console.WriteLine($"Image saved: {imagePath}");
             imageCount++;
         }
     }
 }

I found out that this line

// Assign RTF content to the RichTextBox
richTextBox.Rtf = rtfContent;

doesn't copy rtfContent to richTextBox full. It copies like 20 lines.

I am no RTF expert, so I don't understand why it's not being fully copied, nor how I can make it so, and thus the questions:

Why is it not copying the contents fully? How could I fix this?