If you are facing an issue of Outlook 365 search not working, then the best alternative is to repair Outlook 365. To repair it, here’s what you have to do:
Open the control panel and proceed to programs > uninstall a program.
Search and look out for Microsoft 365.
Tap to change the button and select quick repair.
Now, it will allow performing Microsoft 365 to repair.
Lastly, restart your device and see whether the Outlook 365 search not working issue is resolved or not.