You missed the \n at the end of the string. So it just pushes the string into the output buffer, but the buffer is never flushed.
You could try fflush(stdout) behind the printf. Or just add the \n to the string.
Another possibility would be to use proto/dos.h instead of stdio.h and Printf instead of printf. That way you would bypass the ANSI runtime and call AmigaDOS directly. The output buffer will then belong to the console window rather than the C runtime and the console will print out the buffer when the file handle is closed.
