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Problem with the rotation of the mesh on which the light is baked

I want to move an mesh on which the light is baked. So I switch Mobility to Movable and Lightmap Type to Force Surface. Everything works fine, perfect I would say.

The problems is, when I start to rotate the object. It’s getting dark. See gif:

FPAnim

It looks like some normal information doesn’t update after baking, because if you do a re-bake, all the dark spots disappear, but as soon as you start to rotate the mesh again, the problem appears.

Does anyone have any idea how this problem could be solved? All kinds of hacks are welcome.

Repro:

  1. Place Skylight, make it Stationary, choose HDRI Cubemap.
    //You can do without HDRI, but then you have to setup the light in the scene. It has to be stationary!
  2. Place two Static Meshes, make them Movable and set Lightmap Type to Force Surface. Then make one mesh a child of the other.
  3. Build lighting.
  4. Rotate the parent to see changes on child without immediate loss of lightmap information.
    You can do this with only one mesh via simple script in level blueprint, for example.(Event tick → AddWorldRotation, for instance). But only at runtime.

Any help is very much appreciated!

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