Foliage doesn't show up in Landscape Grass Type


I am having a strange problem with my Landscape Grass Type.
Some of my Static Meshes do not show up.
In the attached image *overview.jpg *you see green areas, where my grass should be.
Some static meshes do work (like attached Grasfussel.jpg), others don’t (like attached Grasbueschel.jpg) and I can’t figure out, where the difference is.
I made the meshes in speedtree, they have a similar polycount and size.

Foliage paint works fine with all meshes.

Interestingly, the meshes seem to cost lots of performance.

Does anyone have an idea, where the problem might be?

Hi I have the same problem 4.22.1. Is this a bug?