Landscape painting crash with some materials [Bug?]


I’m working on landscape auto material. Generally no issues, but when I’m hand painting with selected layer, I have no material on landscape part or even worse - crash, what happens few times.

I looks like this:

When on landscape part, I’m trying to paint with this one material, no matter this is spline paint or hand paint, I have no material on this part (or crash as mentioned).

As I see, problem can be in material itself. I use for layers functions created without other changes from base materials included in Content Pack (Epic).

No problem with for example M_Ground_Grass, M_Rock. They are painted on layer without any problems.

But for example, when I use M_Concrete_Tiles, I have always problems - no material or crash. M_Concrete_Tiles is a little more complicated shader, dunno.

Here is no other reason - when I change layer with other material, it works as expected, so rather no issues with auto material itself.

All mentioned materials are included in Content Example Pack and well known.

Any suggestions?