1. Check if the messages are delivered and stored in your mailbox.
2. If you can access the message in the Sent folder, but not in your Inbox folder, check if the message size exceeds the message size limit.
3. Receive the messages with a plain text format.
4. Disable any add-ins that you may be using in Outlook.
5. Try to create a new Outlook profile if all above steps did not help.