heh, not really. The only volume I have is a LightmassImportanceVolume. I think I remember messing with culling settings somewhere at some point but, I don’t really know where to look 
EDIT: Exporting the map on another (way different) project breaks too.
EDIT2: Hum, I just noticed the Landscape’s Max LODLevel was on -1 (How?), I just put it on 1 and, it works out.
Thing is, I just didn’t touch this before, it just… broke. I can’t put it back on -1 either apparently.