We have turned on the TinyMCE module and set the Body flavor to html. Unfortunately, though, the editor control does not display when we edit or create posts. Currently, we're working around this using LiveWriter to publish. What do you know about why TinyMCE wouldn't be working?

The problem was that I was using the markdown flavor for the Body Part without having enabled the Markdown module. Here is how I fixed it:
Option 1: Enable Markdown
Use this option if you want to keep using markdown.
Option 2: Using HTML not Markdown
Use this option if you'd like to use HTML instead of markdown.
HTML