we are running into a similar issue with individual keys when using them with xcodebuild. Are they supported by xcodebuild 15.4 or later?
xcodebuild -exportArchive -archivePath path/to/my.xcarchive -exportOptionsPlist my-options.plist -allowProvisioningUpdates -authenticationKeyIssuerID issuer-id -authenticationKeyID auth-key-id -authenticationKeyPath my/AuthKey_some-id.p8
Error: Unable to authenticate with App Store Connect (Error Domain=ITunesConnectionOperationErrorDomain Code=-19000 "Failure to authenticate." UserInfo={NSLocalizedRecoverySuggestion=Failure to authenticate., NSLocalizedFailureReason=App Store operation failed., NSLocalizedDescription=Failure to authenticate.}))
error: exportArchive: No Accounts with App Store Connect Access