OK so load up Italio 84.
You should see MOD WHEEL set up already for OSC PITCH, change it to all oscillators -> Waveshaper twist.
Now go to second oscillator and change the wave to Vintage Saw 1
Try it now.
And then try this...
Load up creamy Poly
Under "eg" section turn up the time pot all the way.
There are already two mod wheel settings, change them both to all oscillators -> Waveshaper twist.
Change the second oscillator to Vintage Square 1.
Try it now.
With other presets it may work straight out of the box.
I think you just need to customize the presets to your requirements, not all presets are going to work out the box the way you want it.
If you are to nail down a possible bug it's probably best to do it from INITIALIZE PROGRAM as there are too many variables in a patch to nail anything down, however right now I'm not seeing a bug, rather patches that may not be tailored to your specific requirements.
Oh and the gotcha that caught me out, make sure "MIDI learn" is off for everything.
BTW I'm not sure how deep your knowledge is in this area (it may be better than mine), but this is a great tutorial I strongly recommend regardless of knowhow:
http://www.groove3.com/str/z3ta-explained.html Cheers...