Can't select base of Prefab Variant or any greyed out field in a inspector. 2019.4.13f1.

Workaround for selecting a base. Create new script in an "Editor" folder and paste this code to it. After right clicking on any prefab variant, button in "Tools" should appear .

 using UnityEditor;
 
 public class PrefabsMenuItem
 {
     [MenuItem("Assets/Tools/Show Base of Prefab Variant", priority = 18)]
     public static void PingBaseOfPrefabVariant()
     {
         GameObject[] gameObjects = Selection.GetFiltered<GameObject>(SelectionMode.Assets);
 
         GameObject baseOfPrefab = PrefabUtility.GetCorrespondingObjectFromSource(gameObjects[0]);
         EditorGUIUtility.PingObject(baseOfPrefab);
     }
 
     [MenuItem("Assets/Tools/Show Base of Prefab Variant", priority = 18, validate = true)]
     public static bool PingBaseOfPrefabVariantValidate()
     {
         GameObject[] gameObjects = Selection.GetFiltered<GameObject>(SelectionMode.Assets);
 
         return gameObjects.Length > 0 && PrefabUtility.GetPrefabAssetType(gameObjects[0]) == PrefabAssetType.Variant;
     }
 }