I do not see any problem in the log. Are you able to upload empty file using any other SFTP client?
I have a scheduled process works correctly except that it will not transfer zero length files.
The file transfer method is SFTP and here is the protocol
Session protocol = SSH-2
SSH implementation = SSHD
Encryption algorithm = aes
Compression = No
File transfer protocol = SFTP-3
We are using Version 4.3.7 (Build 1679)
This is the entry in the scheduled batch file
"C:\Program Files (x86)\WinSCP\winscp.exe" /script=UPSToFtpTest.txt
This is the entries in UPSToFtpTest.txt
option echo on
option batch off
option confirm off
# Download the files