When a Steuard menu does not appear, first confirm that the page placement points to a Menu post that is still published. Every Menu post's ID and copy-ready shortcode are shown under Steuard → Menus — open the post and look below its editor.
Is a menu actually selected? In the Steuard Menu block, pick a Menu post in the Menu dropdown. With the [steuard_menu id="123"] shortcode, confirm the ID matches a published Menu post — the page shows "No published menu was found for this shortcode" when it does not. With the classic meta box, make sure Automatically render a menu on this page is on and a menu is chosen. See Adding Menus with the Block Editor or Adding Menus with the Classic Editor.
Is the menu published? A hand-built menu that's still a draft under Steuard → Menus won't display. Publish it first.
Is the source connected and current? For POS-synced menus, go to Steuard → Menu Options → Connections, test the connection, and then check Steuard → Menu Options → Dashboard → Data Freshness. If a refresh failed, see My menu is out of date and My connection won't connect.
Still nothing? If a menu that used to show vanished after a recent change or update, work through Troubleshooting Conflicts. If it still fails, send support the page URL and the safe details in What should I send Steuard support?.
