Lightmass rendering black on some faces

Development Rendering
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1

I have been getting a strange bug where certain faces usually facing in one direction in both positive and negative render completely back. all of a sudden it started happening on meshes I haven’t touched or changed anything on. I have tried what seems like everything, I have re uv’d, changed lightmap res, and countless other things. in one section i have had luck with just simply exporting and re importing while changing nothing and it has fixed the issue. In other areas that fix dosent seem to work. Ill post some images in lit, unlit, and lighitng only.

i tried migrating the level to a fresh project and it fixed some but introduced others. I also tried using cpu lightmass and im getting similar unpredictable errors.
I am at a loss, I dont understand why all of a sudden these meshes started acting like this and I just cant figure out a fix or why its happening.

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2

Might be a silly question, but do you have reflection captures in there?..

3

Maybe you are not using the correct UV map index and the probelmatic meshes have more than one? There is a setting. If you open the mesh in the static mesh editor, “use light map index” or something similar.

4

I am seeing the same issue - 4.22.1 (Oculus Branch). It is very odd. I’ve tried breaking the model apart in different ways then reimporting, different UV layouts, etc., but nothing seems to consistently work.