Blotchy Shadows on Corners

I have a relatively simple map made up of a number of large, very basic shapes. It is primarily lit from a directional light pointing straight down. On all meshes though, I’m getting these weird shadow artifacts on the corners:

I’ve been upscaling the light map resolution to fix this issue, but there seems to be a limit. This mesh above is using a 512 lightmap. The one below is 2048

Why in the world is this happening? I can only assume that it has something to do with the way I built the map but I’m at a loss as to what the correct way would be.

Hi!

I’d say this scene is way too big to get detailed lighting like this… even a 2k lightmap won’t be enough!!
Try instead (distance field) ambient occlusion or cascade shadows!
Do you have LightmassImportanceVolume in the level?
You should also check out this: