Edit: As of 27/03/2017 Microsoft has released Build 7870.2031 of Office 2016 which appears to have fixed the issue. It has for me anyway.
Recently Office 2016 updated itself (Office365 subscription so it uses ClicktoRun) to version 1702 (Build 7870.2024) and this appeared to break searching emails in Outlook 2016.
I thought that maybe the index was corrupt, so I tried triggering a rebuild, but this did not resolve the issue.
To see what version you’re running, have a look in the Account section of a programme in the Office Suite. For example, in Excel open a blank workbook, then click on File on the ribbon, and choose Account in the list on the left-hand side:
There you can see it lists info about the current version, in this case Version 1702 (Build 7870.2024), and lets you alter update options.
As a temporary workaround I disabled automatic updates, and then rolled back to a previous version.
To disable updates, click on Update Options > Disable Updates. I’m in Windows 7, and I got a UAC prompt to confirm the action.
Click on Update Options > View Updates to get to the version history web page. This page shows what’s changed through the different versions. Scroll down near the bottom and you’ll see a Previous Releases section where you can look at the different versions released in previous months.
I decided to try going back just one version, which is listed as Version 1701 (Build 7766.2060).
In order to roll back to a previous version, open a command prompt, enter cd “%programfiles%\common files\microsoft shared\clicktorun” and hit return.
Now you can run the ClicktoRun client and tell it to update to a specific version (using the build number we found above; 7766.2060).
Type in OfficeC2RClient.exe /update user updatetoversion=16.0.7766.2060 and hit return. There won’t be any output in the command line to look at, you’ll just be taken back to the prompt:
Very soon, if not immediately, you should see something like this showing that updates are being downloaded:
Once it’s done, open Outlook and try a search. To start with I got a warning about the index not being complete, so I guess it triggered a rebuild.
In Windows 7 the indexing process slows down when it detects someone is using the computer but you can disable this if you find it is taking a long time to rebuild.