Hello Eric,
Thank you for writing to us. As we have a ribbon button issue i wanted to share this link which you can keep for your future reference as well https://support.microsoft.com/en-us/help/4552163/ribbon-troubleshooting-guide
I had a look through the screenshot and compared with my out of environment . First I wanted to understand what was the exact name of the button - So I accessed CRM organization in the UCI interface and Opened up a lead record .

Once the Lead record opens I appended the command checker " &flags=FCB.CommandChecker=true&ribbondebug=true " - Right after the URL for the record and hit enter .Once I did that I could see the command checker utility.

I clicked on it and located the OOB value

did comparison from the Screen shot and my out of box setup

Now it turns out that we have customized the Out of Box button . Thus the option to hide is not visible . You can have a look at the above screenshot to identify the customization
At this point of time If you want to hide the button then you need to uncustomize it (for oob button) or delete it (for custom buttons).
For Additional inputs you can have a look into this community article which talks about the exact same problem .
https://community.dynamics.com/365/customerservice/f/dynamics-365-for-customer-service-forum/290984/ribbon-workbench-not-allowing-me-to-hide-a-button/835061
Please mark my answer as verified if you found it helpful.Please let me know if you have any other questions around the above.
Bhartendu Pandey
Support Engineer - Customer Engagement- Dynamics CRM/PowerApps/Power Automate
Microsoft