If you haven’t made significant configuration changes in Outlook for a long time and indexing is still ongoing, then the problem with the Outlook index is obvious. If you have recently (up to 3-4 hours) performed these operations, you need to wait until indexing is complete. Outlook search index is rebuilt when you add a new mailbox or Outlook Personal Folder (PST) file, move e-mails between folders, etc. Outlook is currently indexing your items.
