Please add title and title styling options to the new Table of Contents element. Not all pages or posts will always have headings that require a TOC, but since a normal title element isn’t connected to the element, there is no way to have it not render if there is no TOC. This limits its usage in custom layouts. For advanced users adding a custom field and rendering logic could be used, but not really convenient.
UPDATE: Support stated this was by design. New conditional formatting (heading tag count) will likely resolve this for most people.