What's stranger is that your system returned "no breaches" when I tested another email address that I know have shown up in haveibeenpwned.com?

HaveIBeenPwned is a great tool with many years of data breaches accumulated. At InsecureWeb, we focus on recent data breaches that might still pose a risk to our users. Our system's ingestion rate is currently around 1 million records per day. However, as we are a relatively new service, there may still be data breaches that we are yet to detect. If you believe that your email address has been compromised but our system has not detected it, we recommend that you continue to monitor your account for any suspicious activity and report any concerns to us.