Hello there,
You can try to rebuild the Outlook index when Outlook search isn't working
Open Outlook, then select File > Options > Search. Now, select Indexing Options, followed by Advanced. Select Rebuild, and click OK
According to your description, seems that your issue might be more related to the specific FSLogix environment and I'm afraid that Troubleshooting methods used in windows environment might not help much.
The below thread discusses the same issue and you can try out some troubleshooting steps from this and see if that helps you to sort the Issue.
Hope this resolves your Query !!
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