Using Classic Outlook on Windows for personal email, calendar, and contact management
The issue you describe sounds like the issue documented here, Meeting request is missing from organizers calendar (microsoft.com).
The issue is first fixed in Version 2203 (Build 15028.20160) which is now at Current Channel. The Outlook Team is currently working to backport this fix to the other channels.
What version is the client that reproduced the issue (File, Office Account, under About Outlook)?