So I do have a couple of inquiries in regards to how you are creating your landscapes material. I am assuming it is all on one layer, which is why they are all sharing a Landscape Coordinate node.
Could you provide me with either steps, or your project so I can see the issue on my end and possibly figure out what is occurring?
After creating your material and applying it to the landscape, have you created the ‘LandscapeLayerInfo’ for the layer itself?
Since you are not using WPO or Displacement, then we can rule out the bounds idea for now.
Thank you,