WORKING: 3112924 (UE4/Main)
BROKEN: 3160080 (UE4/Release-4.14)
If the user searches for something that produces no results, the search field will disappear and the user cannot clear it. They will have to close and reopen the panel to get the settings back.
This has been seen in multiple areas of the editor (Persona, level editor, material editor).
The Details panel clears out and the search field is removed.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-37293 in the post.