If the table of contents is not displaying, check enabling the app, adding it to the theme, headings, display settings, and the hide metafield, in that order.
If the home screen shows "Enable app," the app is disabled. Select "Enable app."
In the theme editor, open the blog post, product, page, or collection template you want to display. Confirm that the "Table of Contents" app block is there, or an app embed on a vintage theme.
To add it, see the following articles.
The table of contents is built from headings set in the body's rich text. If you are not using heading styles, the table of contents is not displayed. Headings added in theme sections are not included.
Confirm that "Headings" in "Customize the table of contents" matches the levels used in the body. The default is H2 and H3. If the body uses only H2 and you selected only H3, the table of contents is not displayed.
Display on products, pages, and collections is available on the Regular plan. On the Free and Light plans, you can display the table of contents on blog posts only.
If table_of_contents.hidden is 1 on the content, the table of contents is not displayed there. Clear the value or set it to 0, then select "Save."
To set this, see Hide the Table of Contents on Specific Content.
If Position is "Specify class name," confirm that an element with that class name exists on the page. If the element is missing, the table of contents is not displayed.
After you switch themes, add an app block to the target template on the new theme, or add an app embed on a vintage theme.
On an Online Store 2.0 theme, if an app embed is also on, the table of contents can remain in an unexpected place, such as near the footer. Turn the app embed off, and use only the app block.
If the above still does not solve the issue, contact us through the contact form.
When you contact us, include the following information.
The store's myshopify.com domain
The URL of the page you want to display
The theme name
The items you have already checked