Landscape material disappear on low or medium

Hello,

I have landscape made in previous version of unreal.

It worked in next and next version of engine and now it disappears on medium or low.

It happends in editor or build.

It works fine with high.

Generaly I have no idea what caused this, I tried changing multiple things.

It happends even if I change material to empty black one.

Screenshots of landscape settings: Landscape - Album on Imgur

On high or better settings:

292300-high.png

On medium or worse:
(Blue is water.)