[Werewolves GP] My werewolf has a jaw problem when posing with mods

I'm trying to create a mod for werewolves, and the jaw isn't working as it should.

Also of course the other problem is the nose, mouth, and eyes not working, so I use the painting tool, which is a hassle.

In the pictures you see, the werewolf in the Blender app has his jaw open, normal. But in the second picture, in-game werewolf's jaw is tucked in, and not open.

I use WonderfulWhims and Andrew's Pose Player in order to use the poses, and they both have the same problem. I'll see if I can contact someone on Sims4Studio and see if it's a rig problem.

Update: It doesn't change whether I use blender 2.76 or blender 5.0
So it's not Sims4Studio's rig that's the problem.
It's the game itself.