Steps:
1. Open attached project
2. Load SubScene scene
3. Select "rotatingCube" subscene
4. Click "Edit" in Inspector
5. Close the subscene in Inspector
==>
If you do not see two cubes, press "Rebuild Entity Cache"
6. now you see entity in the Scene view
7. Search in Hierarchy for some unrelated GameObject, e.g. "Test"
==>
Everything is greyed out unless Entities

Expected: Entity should be greyed out as well as such as they are not a part of the search result

Note: See attached movie for details

NOTE For the In-context editing of Prefabs feature we depend on this grey out effect to work for entities as well. Info about in-context editing: https://forum.unity.com/threads/in-context-prefab-mode-preview-build.694348/