Dear Saberman_007_,
Good day!
Thank you for posting to Microsoft Community. We are glad to assist.
As per your mentioned description about "Trying To Add A Developer Button To An Outlook Ribbon" ACcording to your provided screenshot it seems you didn't select Developer. Kindly try to check again if you face same situation by going to File-->Options-->Customize Ribbon-->Then make sure that Developer is selected then hit Ok button

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If the issue persist, would you mind offering me below information:
- May I please know the account type are you using? Is it POP, IMAP or Exchange account?
- May I know your current environment? Is It Exchange Hybrid, on-premises exchange (Exchange server) or pure cloud?
- Would you mind to kindly provide the screenshot of the outlook version are you using? Kindly go to File-->Office Account
We are looking forward to your response.
Best regards,
Inema |Community Moderator