This is an old revision of the document!
To search for mails in
https://answers.microsoft.com/de-de/outlook_com/forum/all/outlook-suche-freigegebene-postf%C3%A4cher/a8c55c34-d609-424b-8fd4-3d451c5f0475
Open menu “File”, select “Info”, “Account Settings” and once again “Account settings”. Then select your mail box and click “change”
Deactivate Option “Use Cached Exchange Mode” (if possible):