Why is the keypress only registered on the second press?

Hi, this is a bit specialist but, I'm building a visualizer based on MIDI Input for live music performances. The idea is that you generate an object or whatever (in this case a star) with each press of a key on a MIDI controller keyboard.

I'm using keijiro's MidiJack code. To avoid having to create a separate 'if' statement for each of the 128 values for note numbers in MIDI I'm trying to grab the note number from the 'History' of MIDI Messages as a way of making the program respond to any note inputted. I also have this number displayed on screen.

My problem is that the number onscreen will update upon the first keypress, but it won't actually do anything until the second press of the same key. This isn't very useful for music as most note events are unique in a melody.

Just to clarify that I have had this 100% working with if statements that contain a specified note number, just not with this way of trying to retrieve the number from the list. I really hope someone can explain what I've done wrong, I'm really new to this!

Thanks!

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using MidiJack;
 
 
 
 public class SpawnOBJ : MonoBehaviour
 {
     public Vector3 ObjectSpawnPosition; 
     public GameObject star; //Object to spawn is assigned in Unity Editor
 
     public float flareSize;
 
     private int starCount;
     GameObject[] stars;
 
     string notesGUI;
     string noteStatusGUI;
     string velocityGUI;
     public int noteNumber;
     bool noteOn;
     bool noteOff;
 
     public Texture fader;
     private Color guiColor;
     public float alphaLevel;
     private float t;
     public float duration; //sets fade length in seconds
 
     Controls Controls = new Controls();
     MidiDriver midiDriver;
 
     private void Start()
     {
         starCount = 0;
         Cursor.visible = false;
         guiColor = Color.black;
         alphaLevel = 0.0f;
         notesGUI = 0.ToString();
     }
 
     void Update()
     {
         stars = GameObject.FindGameObjectsWithTag("Star");
         starCount = stars.Length;
 
         Controls.GUIhide();
         Controls.GUIfade();
         Controls.reset();
         Controls.Zoom();
         Controls.Quit();
 
 
         foreach (var message in MidiDriver.Instance.History)
         {
             notesGUI = message.data1.ToString();//Retrieves the note number byte from MIDI interface and converts to string for GUI
             noteStatusGUI = message.status.ToString();
             velocityGUI = message.data2.ToString();
             noteNumber = int.Parse(notesGUI); //Retrieves the note number byte from MIDI interface and converts to int for triggering
         }
 
         noteOn = MidiMaster.GetKeyDown(noteNumber);
         noteOff = MidiMaster.GetKeyUp(noteNumber);
 
         ObjectSpawnPosition = new Vector3
                     (Random.Range(-30f, 30f), Random.Range(-30f, 30f), Random.Range(5f, 120f)); //Random position for star spawning.
 
         flareSize = Random.Range(0.1f, 1f); //Random brightness (size) of star flares.
 
         //if (starCount < 300 && GameObject.Find("endMontage").GetComponent<playVideo>().isPlaying == false) //Sets Star instance limit and stop creation if video is playing
         if (starCount < 300)
         {
             if (noteOn)
             {
                     GameObject.Find("SolarFlare").GetComponent<LensFlare>().brightness = flareSize;
                     Instantiate(star, ObjectSpawnPosition, Quaternion.identity);
                     Debug.Log("MIDI");
             }
           
             if (Input.GetKeyDown(KeyCode.X)) //Spawns star object, used for testing.
             {
                 GameObject.Find("SolarFlare").GetComponent<LensFlare>().brightness = flareSize;
                 Instantiate(star, ObjectSpawnPosition, Quaternion.identity);
             }
         }
     }
 
     private void OnGUI() //Draws the current number of stars onto screen and control hints
     {
         if (Controls.CountGUIEnabled)
         {
             GUI.Label(new Rect(0, 0, 200, 20), "Star Count:" + starCount);
             GUI.Label(new Rect(0, 15, 200, 20), "Press R to Restart");
             GUI.Label(new Rect(0, 30, 200, 20), "Press Z to Zoom");
             GUI.Label(new Rect(0, 45, 200, 20), "Press V to Play Video");
             GUI.Label(new Rect(0, 60, 200, 20), "Press S to Toggle GUI");
             GUI.Label(new Rect(0, 75, 200, 20), "Press F to Fade Out");
             GUI.Label(new Rect(0, 90, 200, 20), "Press Esc to Quit");
             GUI.Label(new Rect(0, 105, 1000, 20), "Status: " + noteStatusGUI + " Note Number: " + notesGUI + " Velocity: " + velocityGUI); //Displays MIDI Note Number in GUI
         }
 
         if (Controls.GUIfadeOut)
         {
             if (t < 1) //sets time reference for fade
             {
                 t += Time.deltaTime / duration;
             }
 
             GUI.color = guiColor;
             guiColor.a = alphaLevel;
             alphaLevel = Mathf.SmoothStep(-0.5f, 1, t); //Fades texture alpha from 0 to 1
             GUI.DrawTexture(new Rect(0, 0, Screen.width, Screen.height), fader, ScaleMode.StretchToFill, true, 10.0F); //Draws texture over screen
         }
     }
 
 }