Is there a log of activity ? Auto-cache feature

Specially about the PRO Auto-cache engine feature ? I configured it with a sitemap index type, there are something like around 80k if not more urls to process there, but cached files stats grows at very low rate, so i’m not sure if it’s processing or not sitemap. There is no error related on errors.log
, On the access log there are few entries with the user agent that plugin supposedly uses, and only requesting the sitemap index itself, not any content url.

Worth it to mention, auto.engine is the only reason that made me took premium version, if this doesn’t work, i will ask for refund within 14 days.