Hopefully there looking at there Apple developer 'feedback' system, as I have posted this issue through that channel as well :)

Just for clarity, as I read some mixed comments, in my case, if I search using spotlight directly, it returns files and email messages that meet the search criteria, there is no issue with that, but the actual search function in the Outlook app does not return results in my case.

Glad you were able to get help out of Microsoft, but the first part in deleting the application is not an acceptable option, for users that have lots of accounts and messages, this is to much effort, quite a poor response from them in my view, the second part, most of us have already tried this from a previous Microsoft suggestion, this does not work either.

Indeed, it is a major issue for me as I use Outlook for five accounts including work account, I need this to be fixed :) I really don't want to have to roll back the OS version to 12.0.1, that's a pain.

I just noticed an update to Microsoft Outlook, version 16.56, updated and tested this, again the search function does not work....thinking it's an Apple issue, hope they are reading these messages and looking into it, it's a real pain.

Just did a full re-index, no change..... still broken :(

Yep, its broken on 12.1 now and I can't get it sorted using the above solution. Hope this gets fixed somehow as its a real pain.