Until Qt Creator 10, console applications output appeared directly in the terminal (both stdout and stderr). With Qt Creator 11, the output is buffered, appears in chunks, and sometimes doesn't appear at all (for instance, if the application writes less than the buffered characters, the output is delayed until it reaches the threshold).

Another issue is that stdout and stderr are interleaved. Probably the cause for QTCREATORBUG-29030.

This is most probably due to the changes in the process stub.