I have played around with Xcode's identity settings and the Keychain Access app in the past. Under Xcode's "Accounts," I have one Apple ID listed. It has a listing under "Personal Team," and Free under iOS and Mac. When I view the details, I have the "iOS Development" and "Mac Development" signing idenities active. I clicked "Create" for the Mac one, but there are no provisioning profiles on the bottom pane, just an option to "Reset" the signing identity, which doesn't fix things.
I created a new Xcode project,and selected "Apple ID" under "Signing." (It was "Developer" or Apple ID until I pressed the button and presumably it checked which on I had.) The status below it says "No code signing identities found" and "No valid signing identities (i.e. certificate and private key pair) matching the team ID 'XXXXXXXXXX' were found." When I press the "Fix Issue" button below that, I get a brief status bar then "The selected team does not have a program membership that is eligible for this feature. If you need assistance, please contact Apple Developer Program Support. https://developer.apple.com/support"
Looking at Keychain Access, I have a "Mac Developer" entry, with my e-mail but a different XXXXXXXXXX value. There is a private key under its disclosure triangle, but the main status bar says "This certificate has an invalid issuer." (It's not expired, though.)
Is there a way to fix this? Or at least reset everything so I can start over (with the same Apple ID)?