Oh, sorry. I’d say around 10 minutes or so…? I think the log said something along those lines. My PC isn’t modern, but it’s still no slouch. But it’s mid-range. I’ll take a look into the Static Mesh Editor and the Lightmap UVs though. Thanks.
EDIT: As to the barn mesh where it goes black - after building the lighting, it says Object has wrapping UVs.