I'm having an issue as well.
I have the multiport setup in Logic X with VEP and everything is great until I try and add more than one instrument into an instance of Kontakt. The first instrument outputs correctly to it's port & midi channel, but the subsequent instruments do not. I would like to fix this so that I don't have to run a separate instance of Kontakt outside of VEP in Logic.
Thoughts?
--Lee