You mention both "modwheel" (in the thread title) and "pitchbend" elsewhere.
I tried both with the patch you mention in standalone mode (desktop app, not via VST in SONAR). Pitchbend worked very smoothly, both up and down, and always returned to the note I was playing on my keyboard when I released the wheel from any position. The modwheel produced some interesting variation, but, again, it was smooth and predictable.
So far, I'm not able to recreate your issue.
If you have Z3TA instantiated in SONAR, please provide additional info (again, items 1-3 above). What audio i/f? What sample rate? What buffer size? If not SONAR on a PC, what?
EDIT: One thing that was weird for me was, for the factory content patches (at least the one you mentioned), Z3TA tried to access Drive E: 3-4 times, popping up an error message which I cancelled, before loading the patch. That doesn't happen with any of the (many) other patches for Z3TA+2 that I've installed. Need to check that out.
EDIT 2: Just checked. It's only that specific patch that's looking for Drive E:. None of the others I tried in Factory Content do that. So, TRY A DIFFERENT PATCH. SAME PROBLEM?