Lightmap UV's messing up during light bake

Hello Everyone,

I was experimenting with ue4 to get most out of its light bakes. During my tests I noticed weird behavior. My lightmap UV’s change or move during the baking process.

Lighmap UV’s are unwrapped by hand. I made lightmap pixels snap to the corners to avoid light leaking. Somehow they change during light baking and the pixels wont align with the corners anymore.

( Im open for better and easier solutions to avoid light leaking. )

Before Bake:

After Bake:


My settings:

  • Using HDR image

  • Skylight lower hemisphere solid color is unchecked

  • All lights are stationary

  • Each wall is a separate mesh

If necessary I can Upload the project