The 2nd carnotaurus AA has always been moving in the past couple months. What's been "broken" is the track it's on. Usually the AA starts much further back, hidden from view, then chases your vehicle as you escape, moving along its track.
I was there in October and it was indeed in B-mode. The AA moves (its head, mouth, and arms), but it was stationary in place near the ride path/vehicle.
I haven't been able to find a recent video to actually confirm that it's chasing again, but reports do indicate it is doing so again.
You can also tell by looking at the projected scrim.
In A-mode, the AA is blocking the blue scrim.
View attachment 828842
In B-mode, the AA is already passed the blue scrim.
View attachment 828843
Here's A-mode with the carnotaurus chasing the vehicle:
Then B-mode with the carnotaurus stationery: