I regened LOD and I get mountains and cliffs popin, not even sure if tree LOD is propered generated either. Not sure what causes that. I use Anvil as a base, the only mod that has anything to do with landscape is Northern Scenery which only adds stuff and I don't think it touches any vanilla assets or anything. Here some SS:
Missing texture folder on SSELODGen_Output when generatin Terrain LOD, not sure what causes that, here's the log...
LODGen_log.txt
If needed, I'll provide extra information.