Shape Key Issue

So, when trying to add a new shape-key for face flexes to my model port, it breaks the entire model when setting the key to 1:[/t]
^ Before setting the newest key to 1


^After setting the newest key to 1

I don’t know why this happens, but I encountered this before. Does anyone know how to fix this?

a desperate bump for aid

How exactly did you add new shape key?

I clicked the mesh and went to the Object Data panel, scrolled down and clicked the + button on the Shape Keys window.

I still need help with this.

Select new shape, then in Edit Mode sculpt new target shape. Don’t edit basis shape for face sculpting as it usually screws the rest shapes.

I’m not even face sculpting. I’m adding facial flexes for Source faceposing.