Suggested contacts / Recent people suggestions not showing in the Outlook Search box

Hello,

I am using the Outlook desktop app on Windows to manage two IMAP/SMTP email accounts.

Whenever I start typing names of people / contacts on the Outlook Search box, the dropdown menu does not show any suggestions, but only the history of my recent searches (see picture below).

I somehow thought that this could have to do with some indexing issues, I have deleted and rebuilt the index but nothing has changed.

Many thanks in advance for any tips on this matter.