I’ve created new images for comparison, because I didn’t save the original ones. You can overlay the 3 images to see the differences between wireframe, skin and material with color only.
I don’t even use auto exposure but have set a lower value for the sunlight directional light and the scene looks as it looked before the update.
In my opinion it still has to do something with the skincache, because the shadowed area has a morph target applied and ue4 for some reason doesn’t like morph targets.
It assumes a false orientation of the triangles when it comes to shading. If I let the sun run a full day cycle I can see that UE thinks that area has a “hole”.
In the past the checkbox for support recompute skincache worked and removed this (and added ugly seams everywhere), but now none of the corresponding settings work.
I will have to import a new character and make some further test, but it has definitively something to do with the morph targets.