It is not possible to change permissions in File Manager, because the option "change permissions" is missing. Why this option is missing? How to revert it back?
Such situation may take a place when additional FTP user is created for subscription and it set manually/added before main FTP user in
/etc/passwd. Such behaviour is confirmed as a software issue #PPA-2084 that was fixed in PA 11.5 MU#11.
In order to fix the issue please install update 11 as described in the article.