Unity Button Responding Very Slowly

I have several buttons that the user is meant to click on them and it would run a function: SetMultiples() and update some game statistics. However, it seems that rather than executing the function immediately, there is a consider delay of 4-5 seconds before the function is called.

I have tried to call the SetMultiples() to respond to a certain keyboard and it seem to run the function immediately.

 using System.Collections;
 using UnityEngine.UI;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class MultiplesButtonClick : MonoBehaviour {
     public PlayerSelection playerSelection; //enum player selection variable
     public Button assignedButton;           //button assigned to this script
     public GameObject planetManager;        //reference to planet manager
     public Color selectedColor;
     public Color originalColor;
     // Use this for initialization
     void Start () {
         planetManager = GameObject.FindGameObjectWithTag("PlanetManager");
         assignedButton = GetComponent<Button>();
         assignedButton.onClick.AddListener(SetMultipes);
         originalColor = GetComponent<Button>().colors.normalColor;
         selectedColor = Color.gray;
     }
     
     // Update is called once per frame
     void Update () {
         
     }
 
     //Function to set the multiples player wants to buy/sell
     void SetMultipes()
     {
         int qty = 0;
         switch (playerSelection)
         {
             case PlayerSelection.ONE:
                 qty = 1;
                 break;
             case PlayerSelection.FIVE:
                 qty = 5;
                 break;
             case PlayerSelection.TEN:
                 qty = 10;
                 break;
         }
 
         if (planetManager)
         {
             planetManager.GetComponent<PlanetManager>().ShowMultiples(qty);
         }
     }
 }

Can anyone explain to me what am I doing wrongly to cause the delay? I have attached a screen shot of how I have arranged my UI canvas. This script is attached to "One", "Five", "Ten" which are all butttons.

This shows the settings on the canvas itself