Piano roll no audio on external MIDI during note editing


I don’t know if this is a bug or i cant be’ able to do this :

I have a MIDI track with no internal instrument assigned
The midi track play an external instrument via cck (nord lead a1 that is class compliant)
When i play the sequence the nord a1 is played by the midi track but…

But when I edit the midi track …move a note, hit the piano roll the nord a1 don’t play !

It will be’ usefull if the external instrument play notes while i edit the midi track…

Please there is a way to obtain this ?

Thank you