golang pprof through http got empty profile output

Question

We use the code below to register http endpoints and do pprof through http. However, we got almost empty output for a 30-seconds CPU profiling. Any suggestions on what we missed?

func pprofRouter(router *httprouter.Router) {
    router.HandlerFunc(http.MethodGet, "/debug/pprof/", pprof.Index)
    router.HandlerFunc(http.MethodGet, "/debug/pprof/cmdline", pprof.Cmdline)
    router.HandlerFunc(http.MethodGet, "/debug/pprof/profile", pprof.Profile)
    router.HandlerFunc(http.MethodGet, "/debug/pprof/symbol", pprof.Symbol)
    router.HandlerFunc(http.MethodGet, "/debug/pprof/trace", pprof.Trace)

    router.Handler(http.MethodGet, "/debug/pprof/goroutine", pprof.Handler("goroutine"))
    router.Handler(http.MethodGet, "/debug/pprof/heap", pprof.Handler("heap"))
    router.Handler(http.MethodGet, "/debug/pprof/threadcreate", pprof.Handler("threadcreate"))
    router.Handler(http.MethodGet, "/debug/pprof/block", pprof.Handler("block"))
}
....

go func() {
   theRouter := httprouter.New()
   pprofRouter(theRouter)

   profCorsHandler := cors.New(cors.Options{
        AllowCredentials: true,
        MaxAge:           60,
    }).Handler(theRouter)

   pprofServer := http.Server{
        Addr:    "localhost:8997",
        Handler: profCorsHandler,
   }
   launchError := pprofServer.ListenAndServe()
   if launchError != nil {
      logrus.WithError(err)
   }
}()