There are only two ways to cause Decker to navigate to another card: calling the go[] function, or setting deck.card. Zazz itself doesn't do either of these things, so I don't see how it could be the direct cause of the issue you describe.

The normal way to call Zazz functions is from in a self-retriggering view[] event handler for a card, as in the example:

on view do
  zazz.flipbook[frame horses 0.02 (range 15)]
  go[card]
end

If anything in your scripts is overriding the value of the variable "card", it would break this idiom; for example, naming a widget "card".

The first thing I would try to diagnose such an issue is open the listener at the problematic card (in widget mode), type

card

and then evaluate it (press shift + enter). If the result is anything but

<card> 

you have your culprit.