Search result template changes saved but not displaying

Check that the template has been published.

Check the URL and verify that the correct collection/profile/form parameters are defined. The collection parameter must match your search package ID, and the profile parameter must match the results page ID, and should not be suffixed with _preview. The form parameter is optional but if included, must match your template name. If omitted, the template name is assumed to be simple.ftl.

Try adding a simple change (such as prefixing a title with some debug print) and publishing this to ensure that a simple change is displayed

Check the underlying data model to see that any required data is present

Check the modern UI logs for any errors generated when accessing the template

If the template change relates to a more specific piece of functionality (such as IncludeURL or curator), check that the feature is appropriately configured and not generating feature specific errors. Finally, check that the template includes appropriate code to render the feature.