Unity6 broke SpriteAtlas in editor

[VodaLechebna]

Reproduction steps:

1. Create new 2022.3.50f1 project from 3D Core (Built-In Render Pipeline) template
2. Open Window/PackageManager/UnityRegistry and install packages: 2D Sprite, Addressables
3. Open Edit/ProjectSettings/Editor and set SpritePacker/Mode to “Sprite Atlas - V2 Enabled”
4. Create folder Assets/Images and add multiple images inside
5. Set their TextureType to Sprite
6. Create SpriteAtlas and add Assets/Images folder to ObjectsForPacking
7. Mark SpriteAtlas as Addressable
8. Create new C# Script:

using System;
using UnityEngine;
using UnityEngine.AddressableAssets;

public class VisualData : MonoBehaviour
{
    public FigureVisualData[] _icons;
}

[Serializable]
public struct FigureVisualData
{
    public byte Id;
    public AssetReference Icon;
}

9. Create new empty GameObject inside SampleScene and attach VisualData component to it
10. Add new element to Icons list:
    
    
11. Hit Play and confirm that everything works
12. Close project and reopen it in Unity 6000.0.23f1 Editor.
13. Select GameObject in SampleScene and witness errors:
    
    

What is interesting that it’s strictly editor UI error, game builds and runs fine
Fielded bug report

[timtunity3d]

This is a known issue. On the upside, a fix is on the way. You can track it here:

Unity IssueTracker - Exception "IndexOutOfRangeException" is thrown when...