Hi, I am getting these render artifacts with face morph targets. I currently have my head connected to ARkit plugin using the iphone. The gif below illustrates the issue. The mesh deformation when turning on wireframe doesnt look bad and faces do not crash/collaspe into each other. Happens in the corner of lips and on the chin.
Looks like the shader you are using wants to draw outlines there. Does not look like a shadow issue. I can see that from the ear showing up. Which shader material are you using?
We need to see more. It does look like you are using a shader there and it does look like you have outlines rendered. I am still pretty sure this has nothing to do with shadows casting from Unreal Engine. Show us more from the model and the shader it is rendered with.