Strange terrain, exported from WM

I have a problem with exporting terrain from World Machine to UE4. Every exported terrain in my UE has this error. I dont know what is this! Heightmaps are in .r16 files. Maybe it is a problem with editor. Help me please!!

Heghtmap

Oh… I`ve done it!!! It was a problem with World Machine plugin “Snow”! The height output was strange cause of bug in this plugin! Now i have nice mountain terrain

Oh… I`ve done it!!! It was a problem with World Machine plugin “Snow”! The height output was strange cause of bug in this plugin! Now i have nice mountain terrain