hi, thanks for the reply. Doing as you said, I'm not getting the
choose Track > Create Track Stack.
So this is what I'm doing :
creating new project, with the number of audio tracks corresponding to the ones i'll drag and drop in the workspace, and when doing so, selecting "use existing tracks".
When selecting all tracks, I'm just getting the following options : new track ; new audio track ; new software instrument track ; new drummer track ; new track with duplicate settings ; rename track (in the first tray)... and that's it...