Outlook sent items not updating
Also, if the person to whom you assign the task rejects it, you might want to reassign it to someone else.To assign a task, you first create the task, and then send it as a task request to someone.I know they have been sent but I cannot locate them.
Although not a change from past behavior, Outlook 20 users can configure where the sent items for IMAP email accounts are stored.
Important Sent Items Update is hosted on MS Azure servers.
The service is totally independent of your mail flow and the functioning of your Office 365 tenant, which means it has no influence on your email processing and delivery time. Moreover, Sent Items Update does not require any service accounts to operate as the entire authentication and authorization process uses OAuth 2.0. Important Be aware that the updating process starts after an email is passed to EOP, so it may take from a few to over a dozen seconds before a user sees an updated message in the Sent Items folder.
This option was removed from Outlook 2013 and newer.
First, check your options and verify you are saving sent items.