Material preview problem after use of landscapelayerblend node

Hello. I’ve created material for my landscape. I used landscapelayerblend to set the automatic materials on it. But when i use this node the material preview becomes solid black color in the content browser, however I still can see the material preview in viewport of material asset. But when I create material instance, the instance has black content browser preview too and has black preview even in the asset viewport. Some pictures of it:


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