public_html ownership issues and related media library issue

The initial issue was that files uploaded to the media library and were not copied to the correct locations (user description "I don't see thumbnails and can't edit files in Media Library").
It turned out to be a public_html ownership issue where the webserver was running as "nobody:nobody" but the folder was owned by user and group of the user.

Changing recurrently ownership of public_html folder (user only) to nobody solved issues with the site.
However, the user is now unable to access public_html via FTP (user is denied) or cPanel (directory is open but looks empty even though it really isn't).