The multi oscillator function has never worked for me. 

On the factory presets I can hear the oscillators spread and I can change the spread value and hear the expected effect. However when I try to change the spread type (for example from Multi-Free to Multi-Sync) they will suddenly become a single oscillator and cannot be changed back. 

Also when I initialise a patch multi oscillators cannot be engaged. I can select them but they have the sound of a basic single osc.

Occasionally I see "spread" instead of "Phase" when I select a multi oscillator but the sound is that of a single osc.

I have had this problems since my first install on OSX 10.6.8, I am now running 2.1.1 on 10.8.3 and it still exists.
My Primary host is Cubase 5.5.

This is a pretty awful bug, the multi oscillators are one of the main features in Z3ta 2 IMO. Not being able to use them in my own patches renders the plugin unfit for purpose.

This is also an issue for me.
 
OSX 10.7.5
Z 2.1.1
Cubase 7.0.5 (& earlier)

Same problems here, OSX 10.8.4, z3t4+ 2.1.1, Cubase 7.05.
 
It seems to be a gui bug to me, since the functionalities work fine through automation, so (this is C7.x specific) I changed the parameters order in the Remote Control editor so the oscillator mode controls are the first six controls, so they are the default to Quick Controls, which I can quickly access through an external midi controls... It's a workaround, but it works.