TextMesh Pro Text stuttering because it's in a vertical layout?

I'm trying to get text to fade in one letter at a time and it works, except when I make the text a child of a Vertical Layout Group. Then the text often stutters whenever a letter gets added as you can see in the video below. The top text is the child of a Vertical Layout Group and the bottom is the exact same object and scripts, just without being the child of a layout group.

I tried forcing a rebuild of the layout whenever a letter got added but that didn't see to have any affect.

I really have no idea why the layout would be messing with the text mesh in a way that would cause this. Do you have any ideas? Thanks in advance.

Here's the scripts for the letter fading.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using TMPro;
4. using UnityEngine;
5. using UnityEngine.UI;
6.  
7. public class FadeLetterDebug : MonoBehaviour
8. {
9.     // Start is called before the first frame update
10.     void Start()
11.     {
12.         StartCoroutine(AddLetters());
13.     }
14.  
15.     private IEnumerator AddLetters()
16.     {
17.         FadeLetterController fadeLetterController = GetComponent<FadeLetterController>();
18.         TextMeshProUGUI textComp = GetComponent<TextMeshProUGUI>();
19.  
20.         while (true)
21.         {
22.             textComp.text += "A";
23.             fadeLetterController.CharAdded();
24.             LayoutRebuilder.ForceRebuildLayoutImmediate(transform.parent.GetComponent<RectTransform>());
25.            
26.             yield return new WaitForSeconds(1f);
27.         }
28.        
29.     }
30.  
31. }
32.  

Code (CSharp):

1. using System;
2. using System.Collections;
3. using System.Collections.Generic;
4. using UnityEngine;
5. using TMPro;
6. using System.Text;
7.  
8. [RequireComponent(typeof(TextMeshProUGUI))]
9. public class FadeLetterController : MonoBehaviour
10. {
11.     private TextMeshProUGUI textComponent;
12.  
13.     [SerializeField] private float textSpeed = 1.5f;
14.  
15.     private List<LetterAlpha> letterAlphas = new List<LetterAlpha>();
16.  
17.     private int currentLetter = 0;
18.  
19.     class LetterAlpha
20.     {
21.         public int CharIndex { get; set; }
22.         public int Alpha { get; set; } = 0;
23.  
24.         // Stores a reference to the text object this letter belongs to
25.         public TextMeshProUGUI TextComp { get; set; }
26.  
27.         public LetterAlpha(int index, TextMeshProUGUI text)
28.         {
29.             CharIndex = index;
30.             TextComp = text;
31.         }
32.     }
33.  
34.     private void Awake()
35.     {
36.         textComponent = GetComponent<TextMeshProUGUI>();
37.     }
38.    
39.     public void CharAdded()
40.     {
41.         // Force the text object to update right away so we can have geometry to modify right from the start.
42.         textComponent.ForceMeshUpdate();
43.  
44.         StartCoroutine(FadeInLetter(currentLetter));
45.  
46.         currentLetter++;
47.     }
48.  
49.     // Increases the given letter's alpha value over time in letterAlphas until its reaches maximum
50.     private IEnumerator FadeInLetter(int letterIndex)
51.     {
52.         LetterAlpha letterAlpha = new LetterAlpha(letterIndex, textComponent);
53.  
54.         letterAlphas.Add(letterAlpha);
55.  
56.         while (letterAlpha.Alpha < 255)
57.         {
58.             letterAlpha.Alpha += (int)((Time.deltaTime / (textSpeed + 2f)) * 255);
59.  
60.             if (letterAlpha.Alpha > 255)
61.             {
62.                 letterAlpha.Alpha = 255;
63.             }
64.  
65.             yield return null;
66.         }
67.  
68.         letterAlphas.Remove(letterAlpha);
69.     }
70.  
71.     // Sets each letter with an entry in letterAlphas to its correct alpha value
72.     private void UpdateLetterAlphas()
73.     {
74.         //Debug.Log("--------------");
75.         foreach (LetterAlpha letterAlpha in letterAlphas)
76.         {
77.             int letterIndex = letterAlpha.CharIndex;
78.             int alpha = letterAlpha.Alpha;
79.  
80.             //Debug.Log("letterIndex = " + letterIndex + " alpha = " + alpha);
81.  
82.             TMP_TextInfo textInfo = letterAlpha.TextComp.textInfo;
83.            
84.             Color32 c0 = letterAlpha.TextComp.color;
85.  
86.             // Get the index of the material used by the current character.
87.             int materialIndex = textInfo.characterInfo[letterIndex].materialReferenceIndex;
88.  
89.             // Get the vertex colors of the mesh used by this text element (character or sprite).
90.             Color32[] newVertexColors = textInfo.meshInfo[materialIndex].colors32;
91.  
92.             // Get the index of the first vertex used by this text element.
93.             int vertexIndex = textInfo.characterInfo[letterIndex].vertexIndex;
94.  
95.             c0 = new Color32(c0.r, c0.g, c0.b, (byte)alpha);
96.  
97.             newVertexColors[vertexIndex + 0] = c0;
98.             newVertexColors[vertexIndex + 1] = c0;
99.             newVertexColors[vertexIndex + 2] = c0;
100.             newVertexColors[vertexIndex + 3] = c0;
101.  
102.             // Pushes (all) updated vertex data to the appropriate meshes when using either the Mesh Renderer or CanvasRenderer.
103.             letterAlpha.TextComp.UpdateVertexData(TMP_VertexDataUpdateFlags.Colors32);
104.         }
105.         //Debug.Log("--------------");
106.     }
107.  
108.     // Updates late so that all of the FadeInLetter coroutines will have run by now
109.     private void LateUpdate()
110.     {
111.         UpdateLetterAlphas();
112.     }
113. }
114.