The backslash character is not being properly preserved when the document is converted from HTML to Markdown syntax. Markdown syntax says that the backslash is a special character, so I escape with with a backslash, e.g "\\"
When the post is saved in the editor, and refreshed, only one backslash remains. When the post is saved again the editor shows no backslashes. Each time the post is saved, the conversion forgets one backslash in each grouping.