Support

There is a discrepancy here.

You are asking me about .htaccess which implies that you're using Apache. Your server's headers say it's using NginX. This can mean one of two things:

A. You misspoke. If you're indeed using NginX you can use the "NginX Config Maker" feature of Admin Tools which is similar to .htaccess Maker but for NginX. In this case you need to include the generated configuration in your NginX config and reload the NginX server. Unlike Apache any changes you make are not taken into account until NginX reloads at which points it reads the configuration, compiles it and keeps its (binary, compiled) rules in memory. That's one of the reasons NginX is so darned fast.

B. You are using NginX as a proxy to Apache. In this case it's up to the NginX configuration to honor the HTTP headers Apache is sending. It's also up to the NginX configuration to tell Apache that it's actually serving an HTTPS request which is the necessary condition for Apache to issue the HSTS header that you've configured in your .htaccess. I do not have experience setting up NginX as a proxy. By the time I had time to spend towards that Apache was already offering an HTTP/2 module, making NginX-as-a-proxy an unnecessarily convoluted exercise. Besides, by smartly configuring Apache (including disabling .htaccess support and putting those rules in the vhost configuration and turning on memory mapping) I was able to achieve comparable throughput. If you need help with this kind of NginX-as-a-proxy configuration you need to ask your host.