Here are some things you can do to troubleshoot the issue:

1. Make sure Outlook is updated [DONE]
2. Check if emails are set up correctly
3. Check if your computer is running slowly or out of space
4. Check if your computer has been severely damaged by a virus
5. Check if your email account is set up correctly
6. Check if you have an email filter set up that is filtering out the emails
7. Run a diagnostic or repair on Outlook