We had an employee who needed to find an email from a few months ago, but when he searched in Outlook the results only went back
The following article from Microsoft did not work. We changed the “Option” to allow more search results, but this didn’t fix the issue.
https://support.microsoft.com/en-us/help/2185146
We ended up creating a new profile and this totally fixed the issue. It took and hour for the mailbox to be completely rebuilt.
Let us know if this helped you…