I think you may have a conflict with your interactive mode -
starts ftp with interactive mode off then you have
I don't think prompt requires or recognizes on/off arguments, it's more like a toggle for interactive mode (see the ftp man page)Edit - and I just spotted "Interactive mode on" in your terminal output.
visual aid -
So you started with interactive mode disabled, then turned it on with prompt; the server timed out without interaction - but I think it should have asked you if you wanted to upload additional files? Maybe not with mput?
You can try commenting out the "prompt off" line and see if uploads go to completion.
Also, can you test your script as written by uploading 4 small text files with completely different names?