hi @hieblertom ,
I have had a look at the project. I have managed to rebuild the picture with Luoshuang’s GPULightmass 5.3.2 Binary It was quite amazing an unexpected and it was very quick.
I have checked the logs for your run and there is nothing wrong with your attempts to rebuild. There are NOT any hardware or software errors in the log of your run.
I expect your want to use Epic GPU Lightmass and I have looked at the code. I only really understand LGPU code so you will need to wait for Epic to fix the problem.
The CPU and LGPU Lightmass both end with “Building Reflection” is running and in the bottom is “Compiler Shaders” counting down CPU and LGPU have different counts. I cannot see where the Shaders are build in Epic GPU, but I wonder if this due to the new addition of Nanite Landscape which is not supported in LGPU or CPU.