Finder connects to FTP server, but has blank file list
If you haven't waited more than ten minutes for the files to appear, you haven't waited long enough. Leave the blank Finder window open, and go make yourself a nice cup of hot coffee/tea/chocolate. When you come back, the files should be there. Should you need to open a subfolder, be prepared for the possibility of another long wait.

If ten minutes sounds like an excessively long time, well, yes it is. While it's cool that Finder natively supports FTP connections, it is in practice an exceptionally poor FTP client.



P.S. I chose ten minutes somewhat arbitrarily as a maximum time limit. It's not a magic number.

P.P.S. To be fair to Apple, not all servers are this slow. But it's not unusual at all.