Pages that do not have a title are automatically excluded from the Table of Contents. You can still choose to list that page in the Table of Contents without adding a title on the page.
To include a page in the Table of Contents:
Navigate to the page in the editor
Click the Settings panel
Beneath the Table of Contents section, deselect "Use the default page title"
Click in the "Page caption" box to type your page title
To learn more about editing the Table of Contents, see help/mycanvas/editing-the-table-of-contents.