TextMesh Pro [3.0.6] TextInfo has incorrect character vertex info when using <font> tags

In my project, I'm doing a bunch of stuff with modifying the mesh data of characters to do things like bouncing/rotating/scaling text. This has been going great, modifying textObject.mesh.vertices while figuring out which vertices I need to modify with textMeshObject.textInfo.characterInfo.vertexIndex and this works reliably.

Then I hit a peculiar problem with I started adding formatting such as the <font="other font"> tag. Suddenly, every other character besides the ones I actually want to modify were being affected. I can't seem to pinpoint what's at play here but I suspect the information I'm getting back from textInfo is render obsolete when doing the font change?

Test Script:
To use: attach this component to a TextMeshPro - Text object and enter Play Mode. The word HAMBURGER should be bobbing up and down. Next, wrap some text in the text field in a valid <font> tag like so:

I'M A <font="Lavanderia Sturdy SDF">HAMBURGER</font> PATTY

Notice that all text besides the text wrapped in the <font> tag is bobbing now.

Code (CSharp):

1. using TMPro;
2. using UnityEngine;
3.  
4. public sealed class TextMeshModifyTest : MonoBehaviour
5. {
6.     #region Members
7.     [SerializeField] private string text = "I'M A HAMBURGER PATTY";
8.     [SerializeField] private Vector2Int range = new Vector2Int(5, 14);
9.     [SerializeField] private float bobAmplitude = 0.25f;
10.     [SerializeField] private float bobFrequency = 10f;
11.  
12.     private TextMeshPro textObject;
13.     private float bobProgress;
14.     private Vector3[] originalVertices;
15.     private Vector3[] modifiedVertices;
16.     #endregion
17.  
18.     #region MonoBehaviour Methods
19.     private void Awake ()
20.     {
21.         textObject = GetComponent<TextMeshPro>();
22.        
23.         if (textObject == null)
24.             return;
25.        
26.         textObject.SetText(text);
27.         textObject.ForceMeshUpdate();
28.         CacheCharacterData();
29.     }
30.  
31.     private void Update ()
32.     {
33.         if (textObject == null)
34.             return;
35.        
36.         ResetModifiedVertices();
37.  
38.         bobProgress += Time.deltaTime * bobFrequency;
39.         float verticalOffset = Mathf.Sin(bobProgress) * bobAmplitude;
40.  
41.         for (int i = range.x; i <= range.y; ++i)
42.         {
43.             if (i < 0 || i >= textObject.textInfo.characterCount)
44.                 continue;
45.  
46.             TMP_CharacterInfo charInfo = textObject.textInfo.characterInfo[i];
47.  
48.             if (!charInfo.isVisible)
49.                 continue;
50.  
51.             int vertexIndex = charInfo.vertexIndex;
52.            
53.             Vector3 offset = verticalOffset * Vector3.up;
54.             modifiedVertices[vertexIndex] += offset;
55.             modifiedVertices[vertexIndex + 1] += offset;
56.             modifiedVertices[vertexIndex + 2] += offset;
57.             modifiedVertices[vertexIndex + 3] += offset;
58.         }
59.        
60.         ApplyModifiedVertices();
61.     }
62.     #endregion
63.  
64.     #region Text Methods
65.     private void CacheCharacterData ()
66.     {
67.         originalVertices = textObject.mesh.vertices;
68.         modifiedVertices = textObject.mesh.vertices;
69.     }
70.  
71.     private void ResetModifiedVertices ()
72.     {
73.         if (originalVertices == null)
74.             return;
75.  
76.         if (modifiedVertices == null || modifiedVertices.Length != originalVertices.Length)
77.         {
78.             modifiedVertices = new Vector3[originalVertices.Length];
79.             System.Array.Copy(originalVertices, modifiedVertices, originalVertices.Length);
80.             return;
81.         }
82.  
83.         int i = 0;
84.         for (i = 0; i < originalVertices.Length; ++i)
85.         {
86.             modifiedVertices[i].x = originalVertices[i].x;
87.             modifiedVertices[i].y = originalVertices[i].y;
88.             modifiedVertices[i].z = originalVertices[i].z;
89.         }
90.     }
91.    
92.     private void ApplyModifiedVertices ()
93.     {
94.         if (ReferenceEquals(textObject, null) || modifiedVertices == null || modifiedVertices.Length == 0)
95.             return;
96.  
97.         textObject.mesh.vertices = modifiedVertices;
98.        
99.         // Push changes into meshes
100.         for (int i = 0; i < textObject.textInfo.meshInfo.Length; i++)
101.         {
102.             textObject.UpdateGeometry(textObject.textInfo.meshInfo[i].mesh, i);
103.         }
104.     }
105.     #endregion
106. }

Other Info:
- Unity 2021.2.8f1
- TextMesh Pro 3.0.6

 

If I'm taking the wrong approach here, I'd really like to know. This has been vexing me for a while now!