Flush the caches does not work Elgg 2.3.16

Even though I click "Flush the caches" and get "The site's caches have been flushed" I still see all the old cache files on the server and Elgg ignores the changes in the language files. For example:


...... (many js cache files)


I also rebooted the server but it did not help.

How to fix the problem?

Thank you very much