The other day I made a major change to some theme code, so I purged the static cache. It has not rebuilt since then. It can create the folders in cache_html, but they remain empty no matter what. I tested by opening an Incognito Window in Chrome and surfing around, follow by logging out and deleting cookies, and ditto
The last change I made was upgrading PHP and ImageMagick - I [i]did not[/i] test the cache at this time.
My server's tough enough to survive (for now) without it, but it's perlexing that this just stopped working without notice, and without error. I'm not even sure where to start looking at this point.
Eh, I'm having a hard time with cache purging in a way that doesn't make me want to drink. Until I can write an extension that lets me purge a page via a click, it's a PITA to flush the pages I need to when I do a coordinated update.
This setup I have is convoluted, and that's absolutely why proxy services are problematic for what I'm doing. I'm not shocked to find out this was an issue too. You should see MediaWiki