Are you referring to the csoundoutput widget? the output that gets printed to the editor in the embedded output component? or the output that gets printed to the floating Csound output window?
If you are editing a file with the editor it will steal all the output messages from Csound so they won’t display in either the csound output widget, or the floating Csound output window.
The csound output widget itself is typically used when debugging plugins as one doesn’t have easy access to the Csound output, as is the case when developing plugins with the editor. But ti will still work so long as you don’t open the editor.
The floating output window is typically used in conjunction with an external text editor. If this doesn’t answer your question, give me a little more detail and we can try again 