Pentaho's get file from FTP step fails randomly. Sometimes it properly downloads the file, sometimes it doesn't returning error:
Error getting files from FTP : Read timed out
The timeout is set to 100 seconds and the read actually fails after less than one seconds.
Contrary to what the Get a file from FTP documentation says about the timeout, it is not in seconds, but in milliseconds.
Change it to any reasonable value like 60000 (1 minute in ms) and your import will work.