Markers and Signal Emitters not working when Timeline in Manual Update Method ?

Yes, timeline needs to playing (i.e. the engine automatically advancing time) for notifications to fire. This avoids scrubbing causing notifications to fire.

If you need to get around it, here's a method that will fire all notifcations in the advanced range using the manual mode update.

        public static void ManualSetWithNotifications(PlayableDirector director, double time)
         {
             if (director == null || !director.playableGraph.IsValid() || director.timeUpdateMode != DirectorUpdateMode.Manual)
                 return;
             
             var oldTime = director.time;
             director.time = time;
             for (int i = 0; i < director.playableGraph.GetOutputCount(); i++)
             {
                 var output = director.playableGraph.GetOutput(i);
                 var playable = output.GetSourcePlayable().GetInput(i);
                 var track = output.GetReferenceObject() as TrackAsset;
                 if (track == null)
                     continue;
 
                 foreach (var m in track.GetMarkers().OfType<Marker>())
                 {
                     if (!(m is INotification))
                         continue;
 
                     bool fire = (m.time >= oldTime && m.time < time) || (m.time > time && m.time <= oldTime);
                     if (fire)
                         output.PushNotification(playable, m as INotification);
                 }
             }
             director.Evaluate();
         }