Experienced this error on multiple levels and disabling Cast Shadows on the Directional Lights in the level prevented this error from occurring. I’m not sure why this prevents the error, though.
Update - I used the DumpUnbuiltLightIteractions command and discovered there were FoliageInstancedStaticMeshComponents in the level (despite how no foliage was added) - I think this occurred after migrating assets from another project.
To resolve this issue, I created a blueprint actor that would search for and destroy and the InstancedFoliageActor in its Construction Script. Then the lighting would build properly with Cast Shadows enabled. So, I think it is because those components that ended up in the level didn’t support static lighting as the other user said.