Certificate issues (like a missing padlock) can occur as a result of various different scenarios. If you believe there might be an issue related to your SSL certificate or certificate installation, the first action you can take is navigating to SSL Labs and running an SSL analysis for your domain.
About SSL Labs
SSL Labs is a trusted third-party SSL analysis platform. However, please note that SSL Labs is not a partner of ZeroSSL, which means you will need to contact them directly about any issues you may be seeing related to SSL Labs.
If the analysis of your domain is successful and no problems were detected for your SSL certificate, the ourcome will look similar to the result in the image below.
If the analysis found problems related to your certificate chain, your intermediate certificate (in ZeroSSL, the file is called ca_bundle.crt) might be missing or invalid. Find an example SSL Labs result below.
In case your certificate chain is flagged as "Incomplete" please navigate to the Install Certificate section of this Help Center, follow the installation steps provided for your server platform and run another analysis via SSL Labs.
If you are still facing issues, please contact support and make sure to bring along your SSL Labs test result.