There are visible black texels on some charts of the terrain after baking with lightmaps. It is possible to observe that some tesellated levels of terrain have the lightmaps correctly assigned, whereas some of them only displays black texels. This behaviour can be observed while navigating in the scene and zooming in and out of terrain.

Steps to reproduce the issue:
1) Download the project http://TerrainHeightmapSquares below and open `TestScene`
2) Generate the lighting
3) Observe the problem