Toggle the trace view. Make sure that the toggle trace view button is depressed as in the image below.
When this button is enabled, the view may switch to the console window. Just switch back to the ARM CoreSight ITM Live Trace Console. The console should show your characters printing.
Also, make sure that the debug configurations > Debugger > Interface, the Type is set to SWD. and in >Debugger > SWV, the Core Clock is set to 120MHz.