Using Classic Outlook on Windows for personal email, calendar, and contact management
Hi JTH_167,
May I know whether you are using Office 365 Exchange Online account or any 3rd party ISP IMAP account?
If you are using an IMAP email account, please refer to the article to check whether you can subscribe to Sent Items folder so that you can view on your computer. See Choose which IMAP account folders appear in Outlook
Moreover, if you are using Office 365 Business account please use the Office 365 Support and Recovery Assistant (SaRA) tool to set up new Outlook profile to diagnose the problems. See: About the Microsoft Support and Recovery Assistant
Your patience and cooperation will be highly appreciated.
Best regards,
Shyamal