UE4.26.2 - GPU Lightmass noise

I’m unable to figure out why I’m getting this strange noise on a simple box mesh when baking using the official GPU Lightmass plugin. The geometry is quite simple and it seems properly UV unwrapped. The lightmass density is also adequate (I’ve tried also decreasing and increasing it without success). I created this geometry using the built-in modelling tools and I can’t see any issues with it. This is what I’m getting: