Issue: Security headers with blank response

Hi,

I have an issue with the plugin. I want to add some security headers but the response, in some cases, are empty.

For example, I’m trying to set x-content-type-options to nosniff. I save the configuration. To check it, i execute a curl on my web and this is what I receive:

$ curl -IL 
HTTP/2 200 
content-type: text/html; charset=UTF-8
date: Thu, 25 Aug 2022 08:09:53 GMT
server: nginx
x-content-type-options: 
x-frame-options: sameorigin
x-xss-protection: 1; mode=block

The same with x-xss-protection. But in this case I I’ve found a workarround: If I change the value, save it, and change it again to the value I want the header is correctly set. For x-content-type-options this doesn’t work because there is just one possible value.

Thanks in advanced for the help and your work!