@scianoir, @YMMB, Thanks!
Here's what I did
setting > controls > buttons/keeys > slew: delete joystick assignement of all buttons of the joystick column
Careful! this will also deassign the Normal (non slew) node 'joystick' buttons and you'll have to reassign them (flaps, carb, trimmer etc)
Careful! changing stuff in this zone often DISABLES THE CONTROLLER and your logitech will stop being recognized so just click 'Enable Controllers' in setting > controls
Hope this will be useful to fsx users in distress 🙂