Shows all GameObjects in the scene with hideFlags, so you can debug them.

HideFlagsUtility.cs

using UnityEngine;
using UnityEditor;

public static class HideFlagsUtility
{
    [MenuItem("Help/Hide Flags/Show All Objects")]
    private static void ShowAll()
    {
        var allGameObjects = Object.FindObjectsOfType<GameObject>(true);
        foreach (var go in allGameObjects)
        {
            switch (go.hideFlags)
            {
                case HideFlags.HideAndDontSave:
                    go.hideFlags = HideFlags.DontSave;
                    break;
                case HideFlags.HideInHierarchy:
                case HideFlags.HideInInspector:
                    go.hideFlags = HideFlags.None;
                    break;
            }
        }
    }
}

This is excellent, thank you! I had a couple of hidden prefab objects in my scene that had broken references, and since they were hidden, I could never see them in the hierarchy. This worked perfectly to show them and let me delete them. Thank you! :)