I've just had an issue with Axway Synchrony Gateway and latest WinSCP 5.5.4. When we upload a file (FTPS) using winscp.com with a batch script, the file is received in the state "Interrupted" on Axway Synchrony Gateway.
To workaround this problem, we have to use an "ls" right after the "put" command. To me it seems, that the connection is closed "too early", causing the transfer to fail in Axway Synchrony Gateway. So the issue is still existing, maybe there was no relation to https://winscp.net/tracker/489 ?