Hi Norm Johnson,
Thank you for reaching out to Microsoft Q&A forum.
Since you have tried Q&A Assist and the issue still persists, it's likely that those messages were moved/deleted at some point or were never saved into Sent items during that period:
At this stage, the recovery depends on what type of mailbox this is:
- If this is a Work/School account: once items are beyond user-facing recovery windows, an admin is needed to search and recover them.
- If you are using personal account: the recovery option is time-limited ("Recover items deleted from this folder" only works while items are still recoverable).
Feel free to also check out this article: Email is missing from your Outlook.com inbox
Since you also stated that you have just updated the Windows version, kindly try revert back to the previous version to see if anything changes.
Thank you for your understanding and time.
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