I also faced the same issue with the latest version of winscp (5.15.3), earlier versions were working fine!!
It works if u set the remote directory to a correct directory, try with root (/) if you have access to it, you might have set it some directory like /home/dir1, which may not exist on the server and while trying to read this, winscp (latest version) hangs, really silly bug
Thanks for your report.
Can you send me an email, so I can send you back a debug version of WinSCP to track the problem? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.
You will find my address (if you log in) in my forum profile.