Erratic blendshape behavior on different skinned meshes

[yanelisZNC55]

I have two rigged characters that have their lips rigged traditionally with joints, but I have a mouth joint skinned to a live blendshape in order to manipulate the entire mouth area. However, I'm encountering an issue with one of the characters and not the other despite having the same setup on both. Attached is a short video illustrating the problem.

The first character's lips are rotated, then the big mouth control is translated forward in Z. The mouth moves forward as you'd expect. That's the behavior I want.

The second character's lips are rotated, then the big mouth control is translated forward in Z. However, the lips start to move diagonally and deforms in unpleasant ways.

Both characters have identical blendShape node deformation order, both blendShape nodes are below the skinCluster in their respective input orders, both targets are 'transform space' in their respective blendshape nodes.

I have tried deleting the blendshape node and starting over the blendshape node for the second character, but the issue persists. I need help identifying what I'm doing wrong.

[stephenkmann]

Most likely it's your deformation order , or what you have the blendShape set to.  Kinda looks like parallel. 

[yanelisZNC55]

I'm afraid they're both set to post-deformation, and they're both in the same order inside the inputs list.

[stephenkmann]

hmm, without seeing the file it's pretty tough to see what is happening

[mcw0]

Is your blendshape origin setting the same for both setups?

[yanelisZNC55]

Both origins are set to local.

I could not find the culprit within the blendshape node or the skin cluster, so I just circumvented the issue and tackled the facial rig a different way.

Still, thank you all for your time.