The latest two updates to WP Fastest Cache will not cache any files on my site. The plugin is activated. The check box to enable it is checked. (Everything is checked except the two beta features.) It just creates an index file in the cache/all/ folder and doesn't cache any visited page. I noticed this when running Pingdom speed tests after resetting the cache for the new version. The site not only wasn't speeding up, but it was actually running much slower than it does with the caching plugin disabled.
When I revert to 0.8.1.5 it works perfectly. I haven't been able to find any compatibility issues with specific plugins I'm using. For now I'm leaving the old version installed because I can't afford to have the site run slow. But if anyone else has run into similar problems and you've been able to pinpoint the issue, I'd love to hear about it.