Can someone tell me what's happened here.

The lady on the right, was an exported model before the 2 updates we were pushed this week and a animation assigned to it in Unreal, so all good.

The one on the left is what happens now. Its not Unreal, because if I re-import my old model its fine, but the latest CC4 export I get this weird eye/mouth pop out as soon as I assign an animation. If I place the new skeletal mesh on the viewport its fine, its just when an animation is assigned