URL is being removed from links in a notes field.

URL is being removed from links in a notes field.

Hello.
I have a notes field that I am using to display links so that the person who is updating a record can download the files from the image fields like in the screenshot below. I am having trouble making links to files that added using a URL instead of uploaded.
 

I have the following code to create a link from the field's value:
  1. if ((input.Image_2  !=  null)  &&  (input.Image_2  !=  ""))
  2. {
  3.     if (Image_2.contains("http") && !(input.Image_2.contains("zohocreator.com") || input.Image_2.contains("zoho.com"))){
  4.       // ...the image is not stored on Zoho.
  5.         attFile = input.Image_2.subString((input.Image_2.lastIndexOf("/")  +  1)).removeLastOccurence("\" border = \"0\">");
  6.         attUrl = thisapp.Global.extractExternalFileURL(input.Image_2);
  7.         input.Photo_Link_2 = "<a href=\"" + attUrl + "\">" + "Download " + attFile + "</a>";
  8.     } else {
  9.        // ... the image was uploaded and is stored in Zoho.
  10.         attUrl = thisapp.Global.buildAttachmentURL(reportName, input.ID.toString(), "Image_2", thisapp.Global.extractFileName(input.Image_2));
  11.         attFile = input.Image_2.subString((input.Image_2.indexOf("_")  +  1)).removeLastOccurence("\" border = \"0\">");
  12.         input.Photo_Link_2 = "<a href=\"" + attUrl + "\">" + "Download " + attFile + "</a>";
  13.     }
  14. }

The functions "extractExternalFileURL()" "buildAttachmentURL()" and "extractFileName()" simply help to generate the correct URL, and all three of them work correctly -- I made sure of that.

The problem I'm having is this:
When I try to add a link to the notes field the href attribute is removed from the string, so it just becomes "<a>Download (file name)</a>".

The links for the images that were uploaded to Zoho from a user's computer work correctly though.

Any ideas why this is happening?

Thanks.