Missing Prefab DontDestroyOnload.,Can´t instantiate dontDestroyOnLoad prefab in other scenes.

Hi everyone!

Im making an audio visualizer using a scene in additive mode for having the UI and in the other scene I have the visuals and that scene can be changed from the UI in order to change the type of visuals. I used a prefab with a DontDestroyOnLoad to drag it into both scenes and be abble to manipulate it, but it seems the prefab is not loading correctly into other scenes and the UI is not working. Also I´ve noticed a DontDestroyLoad Scene is created when you play.

This is part of the prefab script:

 public static LithiumCore ThisIsTheOnly;
 
     void Start () {
 
     
         if (ThisIsTheOnly != null) {
             Destroy (this.gameObject);
             return;
         }
 
 
         ThisIsTheOnly = this;
 
         GameObject.DontDestroyOnLoad (this.gameObject);
 
 
         /////////
         /// 
         ///     
         /// 
         /// 
         _audioSource = GetComponent<AudioSource> ();
 
         _audioSource.clip = Microphone.Start(null, true, 10, 44100);
 
         if (Microphone.devices.Length > 0)
         {
 
             selectedDevice = Microphone.devices[0].ToString();
     
         
         }
 
         //microInput ();
 
     }
 

This is the object where I need to manipulate the prefab:

 public class InputDevice : MonoBehaviour {
 
     public LithiumCore _audioPeer;
 
     public Dropdown _dropdownSelectMicInput;
     // Use this for initialization
 
     // Update is called once per frame
 
     void start(){
 
 
     
 
     }
 
     void Update () {
 
 
 
         for (int i = _dropdownSelectMicInput.options.Count; i < Microphone.devices.Length; i++) {
             Dropdown.OptionData _listItem = new Dropdown.OptionData (Microphone.devices [0].ToString ());
             _dropdownSelectMicInput.options.Add (_listItem);
         }
         for (int i = 0; i < Microphone.devices.Length; i++) {
             _dropdownSelectMicInput.options[i] = new Dropdown.OptionData(Microphone.devices [i].ToString ());
         }
         if (_dropdownSelectMicInput.options.Count > Microphone.devices.Length) {
             _dropdownSelectMicInput.options.RemoveAt(0);
         }
         if (_audioPeer.selectedDevice != _dropdownSelectMicInput.options[_dropdownSelectMicInput.value].text.ToString())
         {
             _audioPeer.selectedDevice = _dropdownSelectMicInput.options[_dropdownSelectMicInput.value].text.ToString();
         }

Here you can see in the inspector that the prefab with the script is missing:

Im new on this, so anything could help.

Thanks :).