When implementing a custom site and modifying any of the pages that use the com.glideapp.servicecatalog_category_view UI page to display the search box when the iframe does not have a header, the search box does not work and fails to land on a result page.
This is expected behavior and only happens after enabling the UI page to display the search box while in a headless object by using the sysparm_headless url argument.
To enable a catalog in a new CMS site, a matching Catalog Site record needs to be created in the [sc_catalog_site] table. This specifies the pages that Service Catalog needs to retrieve in order to work properly. For more information, see Upgrade to Multiple Service Catalogs in the product documentation.
The resulting value of the form search action can display .do instead of the expected (base system) catalog_find.do. This value is populated in the com.glideapp.servicecatalog_category_search template, with the result of the join between the [sc_catalog_site] and the [sc_catalog] tables.
Related Problem: PRB603692