Landscape Grayscale (0-256) values filter

Another problem when filtering grays is an extrange bordered bevel around the selection. This bevel contains the other grays selections.
RyanB, need help with this to finish the landscape material. I dont know if is a bug in UE4.
In the splatmap-texture(TGA 24Bits), if I change the filter from “Default” to “NEAREST” is right… the extrange border goes away, but the selection borders are too much jagged.