These black artifacts still happen. They also happen when I append with flat blue too. I have tried default compression and masks compression. Result is the same as below.
Edit: Upon further tests I noticed this only appears like that on landscape. When the same materials are applied to static meshes the normal maps look fine…
Edit 2: It’s happening on every landscape layer regardless of whether the normal is packed or not. I have simply blended the materials using MatLayerBlend_Standard. Not sure what’s wrong. I’m breaking it down and trying to find the spot that’s causing the issue.