Empty {{wikimacrocontent/}} fails to render/edit

When I create a macro that uses and

{{wikimacrocontent/}}

and has the content marked as optional, the macro should become editable in WYSIWYG mode. However, if the content is empty, you don't get the small widget to click on to start writing your content, this is the behavior on 15.10. On XWiki 17.5.0, you don't get the rendering at all; instead, you get the macro preview (macro:macro_name).