last week I released my first Game Revenge: Rhobar's myth on Steam. There were some problems with slower PCs so I started with a big optimization. I changed some parts of the distance streaming, improved the terrains, removed some bugged objects and optimized all textures. I scaled them down by setting the LODBias in the TextureProperties to a higher count. I have a texture with a specular, normal and heightmap each of the size of 1024px.

diff: LODBias: 1 [512x512]
spec: LODBias: 2 [256x256]
norm: LODBias: 2 [256x256]
height: LODBias: 2 [256x256]

Everything is working great, I reduced the requiered RAM and it's working fine. I can play if from the editor in PIE or with Start on PC. Even in the frontend after cooking I can start it without any problems. But if I install the packed game all textures in a short radius are just black.

Like this:
Click image for larger version

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Can someone say me what's the problem with the game right now?
Thank you!