Hello, I just ran into a similar problem. I have both "Allow anonymous access" and "Allow anonymous upload" checked in cPanel Anonymous FTP Controls. The anonymous user is able to upload files to (and only to this folder) /public_ftp/incoming, however it cannot "see" the contents within /public_ftp/incoming, and well... you can't download what you can't see. Thus, I had to switch to my main account to move the files one level up to allow anonymous downloads.
This may or may not be a feature... but to me it doesn't quite make sense. If I were to allow anonymous upload access to a certain folder, why should anonymous download access from that folder be denied? Personally, I would like to create special FTP accounts (with passwords) that are NOT associated with sub domains, but I don't think that's possible within the FTP Account Maintenance?