Why might caching of static resources on the browser side fail?

Question

htaccess

Caching of static files (css, js) does not work on the site, and none of the options for setting the appropriate headers using htaccess leads to anything. An example of code that is advised everywhere and which should work ironically:

<ifModule mod_headers.c>
    <FilesMatch "\.(js|css|ico|gif|jpg|jpeg|png)$">
        Header set Cache-Control "max-age=604800"
    </FilesMatch>
</IfModule>

Apache is used as a server, cms - ModX Revo