It sounds like your service account might not have the necessary permissions within your Google Analytics account. Even though you’ve set it to have full owner permissions, you might need to go into your Google Analytics account settings and explicitly give your service account email permission to access the account. Try adding the service account email (usually in the format your-service-account@your-project-id.iam.gserviceaccount.com) as a user in your Google Analytics account with the necessary permissions and see if the issue persists.