Such a problem means that optimized files have been removed, but the link to them exists in the cache.
We have the TTL (time-to-live) for files in the /media/pso/s directory to be 2 times the TTL for page cache, so it most likely means there is either a conflict with another caching layer, or an issue in the extension itself.
I'll try to do some more tests, but could you send me (
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) more details about your server setup (Apache version, .htaccess file contents, maybe specific settings in httpd.conf if you changed it)?
