At some point I had to renew my Mac App Store certificates, so I've done so, and now that I'm attempting to build for submission to the app store, I'm getting: "No certificate for team 'My Name' matching '3rd Party Mac Developer Application: My Name (MY_ID)' found".
But where to get a 3rd Party Mac Developer Application certificate? Under Xcode's "Manage Certificates", there is no "3rd Party Mac Developer Application" under the "+" button.
There are only:
Apple Development
Apple Distribution
Mac Installer Distribution
Developer ID Application
Developer ID Installer
(all of which I have).