can not read progress of signe file transfer from external application

I am trying de read output of winscp.com from an extern c++ qt application with readAllStandardOutput() method of QProcess. All was going well (session and authentication outputs are captured and displayed in realtime) until the update of transfer file progression when I am supposed to display the "file_path | .. KB | .. KB/s | binary | ..%" string but nothing happen and it is only displayed after the termination of all the process. I tested my reading process with another console application and it works well but it have to flush the stdout everytime. So is it the case when writing the progress update in winscp?

Thankyou for your help!

Sorry, but WinSCP does not write an intermediate progress, unless it is connected to a live console.