Hi, thank you for your answer. I have tried rebuilding shaders deleting the folders you told me, but it still happened sometimes.
It happened frequently, but it did not happen everytime, and I figured that it did not happen when I open the level in Unlit, so I think it is because the lighting as you said, but the cubemaps I am using are not exceptionally heavy, in fact I only use 2 and one of them is the default GreyTextureCubemap from Unreal.
I tried changing the other cubemap I had to the GreyTextureCubemap as well to see if that cubemap being heavy was the problem, and I think it was? Since I changed that, I have opened the level 5 or 6 times, and I did not get any crash!
Thank you for your help!