No valid SSL certificate shown on browser for download attachment response type

Question

I have deployed a Spring boot web application with REST API endpoint like /download/{pathparam1}/{pathparam2} in tomcat with server.xml configuration as this -

<Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true"
    maxThreads="150" scheme="https" secure="true"
    clientAuth="false" sslProtocol="TLS"
    keystoreFile="/opt/production/app/tomcat/ssl/someorgname.pfx"
    keystoreType="PKCS12"
    keystorePass="someencryptedpassword"/>

The application is working fine but I cannot see a valid certificate for it in the browser for the entire API endpoint https://hostname.com:8443/download/{pathparam1}/{pathparam2}.

The browser however, shows a valid certificate till https://hostname.com:8443/download/{pathparam1} and as soon I append the second path parameter in the URL, no valid certificate can be seen.

If I try to hit https://hostname.com:8443/downloadxyz/{pathparam1}/{pathparam2}, the browser shows a valid certificate for it.

Do I need to make some changes at application configuration or tomcat server settings to fix this?

The .pfx file is shared by my organization for a trusted certificate signed by Entrust.

---

Edit:

Changed the connector port to 8443 in tomcat

Update:

After some hit and trial I have found that this isn't the issue with tomcat or any SSL configurations. But it has something to do with the API itself.

Through my REST API, I am trying to download a .cab file saved in my local server path. And I believe, this is what is causing the issue.

When I try to download a .txt file, then the SSL cert comes as valid, but when I try downloading .cab/.zip/.csv/.xls file, SSL cert appears to be invalid in the browser.

Final Observation:

1. I could conclude that for any endpoint which serves a response that the browser can present inline, the browser shows a valid SSL certificate. But when an endpoint returns a downloadable attachment, the SSL certificate is shown as invalid.

2. Content-Disposition played no role in it. In both the cases, my APIs Content-Disposition was set as attachment.

3. However, apparently this hasn't caused an issue with the application. I can access the endpoint via API gateway and clients are able to consume it without any issues.