To resolve the issue of Outlook not properly sorting or grouping emails by conversation or thread, you should try the following steps:

1. Check your version of Outlook – If you’re using an older version of Outlook, it may be necessary to upgrade to the latest version from Microsoft.com in order to get the best experience.
2. Verify settings – Verify your 'Reading Pane' settings are enabled and set to group emails in conversations.
3. Check the Outlook Email Rules – Make sure email rules are not conflicting with the conversational format you would like your emails to be sorted in.
4. Check out third-party apps – If all else fails, there are several Outlook add-ins available online that can help you with sorting or grouping conversations.