I use my ES-8 and can't figure how to get proper octaves out of my keyboard octaves.

My chain is the following : midi keyboard -> yarns -> ES-8 -> virtual VCO in VCV -> ES-8 ->

When I plug the VCV virtual output to a virtual VCO (all had the same problem : EvenVCO, MacroOscillator, ...), the octaves I hear are always +/- a semitone too short.
Keyboard or Yarns problem ? -> When I change my chain to midi keyboard -> yarns -> real vcos like braids, quadnic, plaits, ... : everything ok.

I even tried this chain : midi keyboard -> yarns -> ES-8 in -> ES-8 out directly -> real vcos : the problem even occurs.

The weakest link is the ES-8 right ? How can I fine tune it so the tracking is proper ?