Search seems broken, always no result (in admin)

Planet 4 Bug Report
===================

Requestor's email: sinder@greenpeace.org
Requestor's Skype: Shawn Inder

Page: https://www.greenpeace.org/canada/wp-admin/edit.php

Description of the issue: Searching even for the first word of a page title
always yields "No pages found" (or "No posts found" when searching for
posts).

NOTE: Shawn already tried to sync elastic search without success.

Tasks

• Issue seems to be fixed now, Investigate in New Relic why this might have happened
• Also consider previous reports of same issue (PLANET-5044, PLANET-5032)
• Investigate about adding an alert whenever ES goes down for any NRO