When logging into the NSX UI, its seen in the URL that the certificate is listed as "Not Secure".
VMware NSX 4.1.2.1
The certificate in use is not trusted by the browser due to the certificate being a self-signed certificate.
Self-signed certificates will show "Not Secure" in the URL, as these certificates are not as secure as CA-Signed certificates. To have a secure certificate, please use CA-signed certificates.
For further NSX certificate information, please review the following documents: