There was also a bug when you have landscapes in HLOD. (it would usually cause an out of memory crash).
It may be a long shot but try excluding the landscapes from HLOD and see it this has an effect on the weird culling.
There was also a bug when you have landscapes in HLOD. (it would usually cause an out of memory crash).
It may be a long shot but try excluding the landscapes from HLOD and see it this has an effect on the weird culling.