Hi!
It looks like I discovered another bug in both UE 4.2.1 and 4.3.0 When you enable Tessellation in the material editor it causes the mesh that’s using this material to render incorrectly in “Lighting Only” mode inside the editor viewport and also when you check “Highlight” check box for the element inside the static mesh editor.
Here’s how my scene looks like in Lit mode inside the viewport using tessellation. Everything looks just fine.
However when I switch to “Lighting only mode” you can see that the meshes that are using material with tessellation enabled are rendering incorrectly. Same thing also happening when you enable “Highlight” element inside the static mesh editor
Unchecking “Enable Crack Free Displacement” for Flat Tessellation seems to fix the issue and the mesh starts to render correctly, but it doesn’t work for PN Triangles
Yurt when you use tessellation the engine can only use the original mesh and UV for lighting. Then that info is applied to the tessellation. That is why most tessellation is done with dynamic lights but like your viewport image if the tessellation isn’t too crazy it looks just fine using baked lighting. So don’t be surprised when your mesh selected is your original on without tessellation shown.
I understand that and I don’t expect to see tessellation in lighting only mode. What I mean is that the mesh is invisible and you only can see weird dots almost like a vertices instead of a low poly mesh. Just open the second attachment called “bug.jpg” and you will see what I mean. I don’t think this is how it supposed to work and this bug is easily replicated just by turning tessellation on in the material editor you don’t even have to plug anything into World Displacement or Tessellation Multiplier. I was able easily replicate this problem using default Epic Games materials. So I’m pretty sure it’s a bug
Thank You for your report. This is a known bug and our Engineers are working on it right now. I do not have a time table on it getting fixed at this moment.
