Search not working on Outlook 16.79 on Mac Sonoma

I had trouble in both New and old, and this method solved my problems. I may add I did it twice. One with a restart and then once again the next day.

For Step 3....

Close Outlook

To switch ON to new outlook use Terminal command:

defaults write com.microsoft.Outlook EnableNewOutlook -integer 2

To switch FROM new outlook back to legacy use Terminal commands:

defaults write com.microsoft.Outlook EnableNewOutlook -integer 1

defaults write com.microsoft.Outlook EnableNewOutlook -integer 0

Reference:

Set preferences for Outlook for Mac - Deploy Office | Microsoft Learn

You can observe status of indexing with Command - Space

Just type: index in Spotlight Search box

I am running Sonoma 14.2.1 and Outlook Legacy. I fixed this problem by:

1. Click on Outlook on the toolbar
2. Hover over Services
3. Click Services Settings
4. Open the Searching tab
5. Checkmark Spotlight
6. Click Done

I don't know which version of Outlook you're referring to (the heading says Outlook 365 for Mac Version 16.79). I am running 16.80, and there is no "Outlook > Preferences > Search > Indexing > Rebuild" selection pathway. There's not even a "Preferences" menu option— it's called "Settings."