Starting from Server 2019, Microsoft has implemented changes to the Windows Search Service indexing options. This alteration affects the search functionality in Outlook, as it now employs per user search indexing. Consequently, administrators are unable to view the indexed locations.

To restore the old method of indexing which I prefer is the following

1. Open up Registry Editor from the start button/search
   • Make sure to backup the Registry entries first
2. Find the following HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Search
   • Create a DWORD EnablePerUserCatalog with a value of 0

You’ll have a couple of options to apply this change. Either enable and start the Windows Search service or restart the VM Virtual Machine. It may take some time depending on the size of the RDS instance, users, and applications, so don’t be frustrated if it does take a while.