Sorry to bother. I’ve been facing this problem from quite a few days. I tried whatever i can to solve this issue but nothing works. The thing is couldn’t even debug why this problem was happening to begin with. So in some scenes when animating the jaw with lips rigger there seems to be a breakdown at some places as shown in the video. If i tweak around the jaw control a little bit the problem goes away. This problem is occurring to me in only a few cases and even if I copy the same values of the lips and jaw to the same rig in another file it works fine. I’m sorry I couldn’t upload the actual file in which the error is occurring as it belongs to the studio.
In this rig I parent constrained the ‘lips_C_crvs’ with ‘mouth_C0_lipup_jnt’ & ‘mouth_C0_liplow_jnt’ for the lips to follow the head properly.
Here is the link showing the issue: https://drive.google.com/open?id=1pORMh6dlLbNiY1i9WJTS-KmnR5qmQynJ