I upgrade from 2.2.2 to 2.2.3 around the same time I moved the site to another server, not sure which one might be the cause if either are.
The plugin (2.1.1) is activated and enabled. In the options menu the 'Cache contents' always show '0 cached pages' and '0 expired pages'. But I do see the cache show up in the cache directory. Viewing the page source it is showing the page isn't cached. The delete cache button does actually delete the cache, but when the page is visited again the cache is created but still shows 0 on the page and wp doesn't use the cached page.
I have used wp-cache on the site for a couple years now with no issue, so I'm kinda stumped.
I have disabled, deactivated and deleted the plugin along with the cache directory and installed the plugin fresh, hasn't helped.
Apache and PHP have also been update recently.