I have a newly installed version of forma.lms (1.4) and the system was initially configured to upload documents via FTP (all connections were good during install), but I am unable to upload any documents.
I found a post from 2012 about the same issue, but the systems menus have changed since then and I am not able to find the same settings.
Main > Configuration > Settings > Advanced
There isn't a File Uploads Whitelist, only File Uploads Path.
I also made sure that all of the folders listed in the paths actually exist on the web server.
Since you mention not being able to upload anything, I am not sure it depends on the list of allowed extensions.