Unity Meta XR All-in-One SDK - there are no Building Blocks

Hi my friend, here the solution:

1. Create a folder named "Editor" in your Assets folder

2. Create a C# script inside called "FixBuildingBlocks.cs" with this code:

using UnityEngine;

using UnityEditor;

public class FixBuildingBlocks : EditorWindow

{

    [MenuItem("Tools/Fix Building Blocks")]

    public static void FixBlocks()

    {

        EditorPrefs.DeleteKey(null);

        Debug.Log("Null key deleted. Restart Unity to see Building Blocks.");

    }

}

3. Save, wait for compilation, then click Tools → Fix Building Blocks

4. Restart Unity completely

ET VOILÁ!