Landscape Layer blend node inconsistency

When the landscape has no textures the landscape layer blend material node will render as the first layer. When painting only holes onto the landscape, the landscape will have a layer texture but still have no blend layers painted, but now the layer blend node will render black instead.

These two cases should be consistent. We should probably render black in both situations.

This seems to be due to the "preview weights" being used, but the if possible the material should only use these for non-landscape vertex factories.

Create a new landscape, setting the material to a landscape material which uses the landscape layer blend material node (Path Removed, see commentsl).
In the landscape properties, set the hole material (Path Removed, see comments).
In the landscape editor, switch to the visibility tool
Paint holes in the landscape
Observe that the landscape turns black around the holes