/startup endpoint not present in native app (using cnb and BufferingApplicationStartup)

Following the guidance here in the Spring Boot docs and having Actuator in the deps + this in main:

public static void main(String[] args) {
    SpringApplication app = new SpringApplication(Thing2Application.class);
    app.setApplicationStartup(new BufferingApplicationStartup(2048));
    app.run(args);
}

The /actuator/startup endpoint is present and populated when running as a standard, JVM-based (WebFlux/RSocket) app, but not when using buildpacks to create a native image. It simply doesn't appear, no indications present.

Is /startup not yet available when creating native Boot apps? If it is, please advise of any additional steps I may have missed exposing it. If not, please let me know and I'll log a request. Thanks!