Landscape Painting Problem

Hi Community

Well, My problem is i made landscape material it has 3 layers each layer has tessellation on
When i applied the landscape mat to landscape i faced two problems :

1 - i got flickring on randoms landscape components ?
And i solved this one by changing Zbound extention.

2 - i cant paint all three different layers, when i paint two layers it is ok but three i get this result ?
i have no ideas how to solve this !
As you can see also there is a message on top left screen ?

landScape Material