It appears that the landscape painting tool is not correctly taking into account deleted landscape sections, resulting in artifacts inside of the weight textures. ...
It appears that the Landmass plugin has a content dependency on the BlueprintMaterialTextureNodes plugin. If the BlueprintMaterialTextureNodes is not loaded, then the blueprint "/Landmass/Landscape ...
This is a regression as it does not happen in //UE5/Release-5.1.1 ...