CORS node on CDN. We already allow CORS on the CDN, so the issue has nothing to do with the server. It is blocked from the browser cache before being pushed to the remote server. When we open a page, the first time the images are stored in the browser cache. Then we open the image in preview mode and click download, now the browser is too "smart" to detect this image is already in the cache and get it straight from the cache.
Can someone explain why the cache is blocked even though the server has CORS enabled.?
Caching a complex topic, I suggest looking at proper documentation.
The performance of web sites and applications can be significantly improved by reusing previously fetched resources. Web caches reduce latency and network traffic and thus lessen the time needed to display resource representations. HTTP caching makes Web sites more responsive.
Caching is a technique that stores a copy of a given resource and serves it back when requested. When a web cache has a requested resource in its store, it intercepts the request and returns a copy of the stored resource instead of redownloading the resource from the originating server. This achieves several goals: it eases the load of the server because it doesn’t need to serve all clients itself, and it improves performance by being closer to the client. In other words, it takes less time to transmit the resource back. For a web site, web caching is a major component in achieving high performance. However, the cache functionality must be configured properly, as not all resources stay identical forever: it's important to cache a resource only until it changes, not longer.