Problem with landscape material. How to solve?

Good morning!
I really don`t understand what is wrong and how to fix it.

Here is screenshot:

Hi PinkPanteRus,

Please post this to the answerhub in the bug reports section (link in signature). In the answerhub post, please include what engine version you are in, a screenshot of your landscape material graph, and what steps you are taking before this occurs.

Thanks a lot! I shall do it.