Frederick, I’m having the same issue. You can check my blog: Dukeo.
For the homepage, everything is working fine.
However, for the posts, the page gets cached properly (I can see the files being created in the cache folder), but if you check the source code, you’ll see that the CDN is not being used.
Moreover, in the source code you’ll notice that the “commented lines” are missing at the end of the page. I suspect that W3TC is not processing anything on the page before caching the .html file.