Unreal Engine 4.27.2 - Problem Building Lighting

Hi

This is primarily for UE4 as I’m following a book on the engine. However, I seem to have an issue with rebuilding the lighting. I’ve created a lit pillar that I’ve converted to a Blueprint, but as soon as I drop one into the scene and build the lighting, it gets stuck. If I place four of them, it gets stuck on 96%. If just one, then 99%.

I’ve tried adding a Lightmass Importance Volume and adjusting that, but it doesn’t appear to help. I’ve also checked the Lightmap Density, but nothing is out of the ordinary. I’ve even adjusted the Lightmap resolution for some of the BSP meshes I’ve blocked in, but it hasn’t helped. Any advice?

Thanks