Action not triggered after Invoke time passed (Invoke called in different script)

The code should output a random action out of 16 after a editable time. The output should currently only be the random number written in the log but it doesn‘t work. Class 1:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Spawner : MonoBehaviour
 {
     public GameObject thisObject;
     public Funktions funktions;
     // Start is called before the first frame update
     void Start()
     {
         funktions = thisObject.GetComponent<Funktions>();
     }
 
     // Update is called once per frame
     void Update()
     {
         
       funktions.DoOnTickTime();
         
     switch(Funktions.randomNumber)
         {
         case 1:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 2:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 3:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 5:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 6:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 7:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 8:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 9:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 10:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 11:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 12:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 13:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 14:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 15:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         case 16:
         Debug.Log(Funktions.randomNumber);
         Funktions.randomNumber = 0;
         break;
 
         
 
         }
     }
 }

Class2:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using System;
 
 public class Funktions : MonoBehaviour
 {   public static float spawnSpeedCount;
     public static int countdownTime = 2;
     public static int randomNumber;
     
         void Start()
         {
             
         }
     //One Tick
     public void OnTick()
     {
         int randomNumber = UnityEngine.Random.Range(1, 17); 
         spawnSpeedCount += 1;
         
     }
     public void DoOnTickTime()
     {if(!IsInvoking("OnTick"))
         {
      Invoke("OnTick", countdownTime);
         }
     }
    
 
     
     
         
 }