Cloudflare Rocket Loader is a pretty advanced but invasive way to make JavaScript non-render-blocking, which <a href="https://wordpress.org/support/topic/rocket-loader-breaking-onload-js-on-linked-css/#post-9263738">Cloudflare still considers Beta</a>. Sometimes Autoptimize & Rocket Loader work together, sometimes they don't. The best approach is to disable Rocket Loader, configure Autoptimize and re-enable Rocket Loader (if you think it can help) after that and test if everything still works.