From what I can tell, what might actually be going on is the Zero Latency feature is still there, only now they've made it all 'smart' & context-sensitive. Which is to say, instead of being there if and when you actually want it, it's now there when the software detects on your behalf you might need it.
To test this theory, go ahead and set your Device Block Size to a ridiculously low level, so that it maxes out your CPU usage. If that makes the little 'Z' button in the track channel pop right back up - as it's just done earlier on today with mine - then the theory is, unfortunately, confirmed.