Im facing a strange issue, in which, it seems to me that static images are being served by php instead of cache.
Google pagespeed insights reports my images as non optimized.
Nginx config is the default one of a wpredis + php7 installation, which contains caching headers, expires for static images and try_files already set for requesting images directly from cache.
I created two instanced ( one with w3tc and one with wpfc option) but they seem to behave exactly the same.
Caching headers can be seen in console, which means to me that caching system works fine, but for some reason, upon first load, static content is being asked by php, causing higher load times.