Our Operations team has identified and mitigated the issue affecting substitution values. We apologize for any inconvenience this caused. Please reach out to our support team with any additional questions: https://support.sendgrid.com.
We are currently investigating reports of substitution values not replacing properly for a subset of our customers. We're actively working to determine the root cause and will provide additional updates shortly. If you have questions or need additional information, please contact SendGrid Support directly: http://support.sendgrid.com