Button wont run sceneloader coroutine-calling functions, but can run it's other functions

explanation/overview: I have a scene loader script that requires buttons to call the functions. Each different scene has a button, where i manually dragged the prefab into the OnClick() object for the appropriate button in each scene. Even though the Sceneloader gameobject is singleton'ed, the buttons still call the non coroutine-starting functions, but if I try to make the buttons call the coroutine-calling functions, for the first scene, it will work for only the first scene and button. in other scenes, the buttons keep giving a "Coroutine couldn't be started because the the game object 'SceneLoader' is inactive! UnityEngine.MonoBehaviour:StartCoroutine (System.Collections.IEnumerator) SceneLoader:FadeLoad () (at Assets/Scripts/SceneLoader.cs:84) UnityEngine.EventSystems.EventSystem:Update () ".

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEditor.Build.Content;
 using UnityEngine;
 using UnityEngine.SceneManagement;
 
 public class SceneLoader : MonoBehaviour
 {
     private CanvasGroup canvasGroup;
 
     void Awake()
     {
         canvasGroup = GetComponentInChildren<CanvasGroup>();
         int sceneLoaderCount = FindObjectsOfType<SceneLoader>().Length;
         if (sceneLoaderCount > 1)
         {
             Destroy(gameObject);
         }
         else
         {
             DontDestroyOnLoad(gameObject);
         }
     }
 
     private void Start()
     {
         StartCoroutine(FadeIn(1));
     }    

      // *** THIS WORKS NORMALLY, EVEN IF THE SCENE LOADER DOESNT HAVE A PREFAB IN EACH SCENE
     public void LoadNextScene()
     {
         int currentSceneIndex = SceneManager.GetActiveScene().buildIndex;
         SceneManager.LoadScene(currentSceneIndex + 1);
     }    
  
     IEnumerator FadeOutLoadFadeIn(float time)
     {
         yield return FadeOut(time);
         LoadNextScene();
         Debug.Log("Fade in");
         yield return FadeIn(time);
         Debug.Log("Fade out");
     }

     IEnumerator FadeOut(float time)
     {
         while (canvasGroup.alpha < 1)
         {
             canvasGroup.alpha += Time.deltaTime / time;
             yield return null;
         }
         //SceneManager.LoadSceneAsync(SceneManager.GetActiveScene().buildIndex +1);
     }
     
     IEnumerator FadeIn(float time)
     {
         while (canvasGroup.alpha > 0)
         {
             canvasGroup.alpha -= Time.deltaTime / time;
             yield return null;
         }
         //SceneManager.LoadSceneAsync(SceneManager.GetActiveScene().buildIndex +1);
     }
 
     // ***I WANT THE BUTTONS TO CALL THIS, BUT IT DOESNT WORK***
     public void FadeLoad()
     {
         StopCoroutine(FadeOutLoadFadeIn(1));
         StartCoroutine(FadeOutLoadFadeIn(1));
     }
 }