Fix Outlook search so it will also search online archive

A Windows 10 user with Office 365 installed on her computer has an issue where whenever she performs a search within Outlook the searches do not search the emails contained within the online archive folder.

This is a big problem since she needs the searches to find whatever is being searched for within Outlook by including both the regular Inbox and the online archive folder.

I have deleted and rebuilt the Windows 10 index and have made sure that the indexing includes Microsoft Outlook but this hasn't fixed the issue.

All the latest Windows 10 and Office updates are installed on this computer.

What can be done to fix this issue so whenever the user searches for anything within Outlook the searches will also search within the online archive folder?