How to create an editor script that contains an array of a class within a list

Hey, been struggling to put together an editor script for my dialogue event class.

I want to have my dialogue reorderable, which would make things infinitely easier when developing my game. However I have ran into an issue where I need to display an array of another class in the inspector. Basically this is what I have so far (I'm new to this so excuse the code if it's bad): Editor Script

 [CustomEditor(typeof(DialogueTrigger))]
 public class _DialogueTriggerEditor : Editor
 {
     private ReorderableList dialogueList;
 
     public void OnEnable(){
         dialogueList = new ReorderableList(serializedObject,
                                             serializedObject.FindProperty("dialogue"),
                                             true, true, true, true);
 
         dialogueList.drawHeaderCallback = (Rect rect) => {
             EditorGUI.LabelField(rect, "Dialogue Events");
         };
 
         dialogueList.onRemoveCallback = (ReorderableList l) => {
             if (EditorUtility.DisplayDialog("Warning!", 
                 "Are you sure you want to delete this Dialogue Event?", "Yes", "No")) {
                 ReorderableList.defaultBehaviours.DoRemoveButton(l);
             }
         };
 
         dialogueList.drawElementCallback = 
         (Rect rect, int index, bool isActive, bool isFocused) => {
         var element = dialogueList.serializedProperty.GetArrayElementAtIndex(index);
             rect.y += 2;
 
             GUIStyle myHeaderStyle = new GUIStyle(EditorStyles.label);
             myHeaderStyle.fontStyle = FontStyle.BoldAndItalic;
             myHeaderStyle.fontSize = 12;
             Color myHeaderColor = Color.blue;
             myHeaderStyle.normal.textColor = myHeaderColor;
             EditorGUI.LabelField (new Rect(rect.width / 2 - 40, rect.y, rect.width, EditorGUIUtility.singleLineHeight), "Dialogue Event " + index, myHeaderStyle);
 
             EditorGUI.PropertyField(
                 new Rect(rect.x, rect.y + 20, rect.width, EditorGUIUtility.singleLineHeight),
                 element.FindPropertyRelative("charName"), new GUIContent("Speaker Name:"));
             EditorGUI.PropertyField(
                 new Rect(rect.x, rect.y + 35, rect.width, 75),
                 element.FindPropertyRelative("sentence"), new GUIContent("Sentence:"));
 
 
             EditorGUI.PropertyField(
                 new Rect(rect.x, rect.y + 115, rect.width, 75),
                 element.FindPropertyRelative("characters"), new GUIContent("Characters"));
             
             EditorGUI.LabelField (new Rect(rect.x, rect.y + 140, rect.width, EditorGUIUtility.singleLineHeight), "Audio Settings", EditorStyles.boldLabel);
             EditorGUI.PropertyField(
                 new Rect(rect.x, rect.y + 155, rect.width, EditorGUIUtility.singleLineHeight),
                 element.FindPropertyRelative("sceneMusic"), new GUIContent("Music:"));
             EditorGUI.PropertyField(
                 new Rect(rect.x, rect.y + 173, rect.width, EditorGUIUtility.singleLineHeight),
                 element.FindPropertyRelative("dialogueSFX"), new GUIContent("Additional SFX:"));
             };
 
             dialogueList.elementHeightCallback = (int index) => {
                 var elementHeight = 4;
 
                 if (elementHeight >= 1)
                 {
                     elementHeight--;
                 }
                 return (EditorGUIUtility.singleLineHeight * 5) + elementHeight * (EditorGUIUtility.singleLineHeight * 2.7f);
             };
     }
 
     public override void OnInspectorGUI() {
         serializedObject.Update();
         dialogueList.DoLayoutList();
         serializedObject.ApplyModifiedProperties();
     }
 }

Basically the "characters" property field is what I want displayed, however the most I've managed to get in the inspector is a foldout GUI that shows nothing.

While it doesn't work with my editor script, it works perfectly fine without it