SSH communication with PI works fine, Can log in as either pi or another user from putty and can do as I wish.
Attempting file transfer using FileZilla or WinSCP to transfer files from Windows 10 machine to my PI fails every time when the PI fails to respond at the end of the transfer. Eventually the connection times out. Upon failure, attempted transfer leaves a zero byte size file on the PI with the correct filename. Attempted to change timeout from 20 seconds to 60 seconds, and even unlimited, but no difference.
Have not found another similar issue after lots of Googling.
Additional clarification. The initial connection works fine with any program. I can create directories and delete zero-length files. But, all file transfers fail.