You can fix this issue by closing the application using the Task Manager. To end the process, please follow the steps mentioned here. Press the control, Alt, and Delete keys together to open the selection field and select Start Task Manager. The next step to fix Outlook 2016 search not working is to select Outlook from the list of all applications on the Task Manager window. Lastly, select the running processes under the Processes tab. Find Outlook here and click on End Process. Please restart Outlook next.
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