Hi Jason, thanks for downloading the Headers Security Advanced & HSTS WP plugin, I am glad you like the plugin.
I am Andrea and I will help you with your issue as quickly as possible, below I will answer your questions:
1) I did a check with hstspreload and I confirm you that I found an issue with the domain scan “penchecks.com”.
response: Error: No HSTS headerResponse error: No HSTS header is present on the response.
2) I confirm you that with the Geekflare tool the HSTS directive for preloading in the list of broswers is recognized.
This is the link where I performed the test (identical to yours):
https://geekflare.com/tools/tests/qv79lk2lg
response: great! HSTS header was found in the HTTP response headers as highlight below.
** I ask if you can confirm that the installed version of the plugin is version number 5.0.04? Is your provider forcing the use of HSTS?
I also found the error you are experiencing with HSTS Preload. Basically the preload is not performed because the declared directive is invalid (strict-transport-security: max-age=31536000).
This is very strange because the Headers Security Advanced & HSTS WP plugin uses that directive for preloading to be more precise the plugin uses (Strict-Transport-Security: max-age=63072000; includeSubDomains; preload).
Don’t worry now we solve everything together in no time ??
TROUBLESHOOTING RESOLUTION:
a) Deactivate the plugin and delete it, once effected this try to reinstall the plugin and save permalinks for safety.
b) If option A had no effect try to confirm that in your .htaccess file you can find the following # Headers Security Advanced & HSTS WP – 5.0.04 and tell me the directive you see with the following name “Strict-Transport-Security”.
I will also leave you the email to get in touch with me even faster [email protected]