Been a long time WinSCP user and have never encountered a problem like this. Was logged in from my Windows 10 PC (running version 5.15.5) to a Raspberry Pi running Kodi (OSMC 2019.11-1) & not really sure what happened but I believe I was disconnected and have not been able to log back in since. I've been trying for days now using different user names / passwords, changing settings on Kodi / WinSCP and just cannot get it working. Right now WinSCP is set on SFTP protocol, although I'm not sure if that's what it was set on when it was working. I have "ENABLE SLL" selected in the Kodi settings menu, was able to PING from my PC to the Pi, tried the default username & password (Pi / Raspberry). After clicking "Log-In", Searching for host, Connecting, Authenticating, Using username, Authenticating with Pre-Entered Password, Access Denied & then the password field.
I'm sorry if I didn't list any other info needed to help. I've never had an issue with this program and have never needed help before and so I don't know what info is needed but would gladly provide it if requested. I enabled session logging level Debug2 and provided pastebin link. Thanks guys.