The equation editor does not render correctly when answering an essay question type. These are screen shots I took on demo.moodle.net. First, note the lack of buttons for the symbols

The reason is the lack of an "active" class. When I put it in manually, in the developer inspector the equation editor is rendered correctly.

It should be noted that student do have access to a correct equation editor in Fórum or a Lesson essay question.

 The screen-shots come from this forum thread. I don't know why they were not showing up here.