Thanks for the quick fix!
Can you post a screenshot of the heightmap as well. It looks like it’s hard steps through layers instead of blending.
It may be necessary for you to add a bit of blur to your image to get a smoother transition.
Here is the first image with the stepping and the imported landscape heightmap:
Here are the landscape results:
Using Photoshop or an image editor you can blur the edges using Guassian Blur (or anything else that gets the same results):
Here is the landscape result:
There may also be some things that could be adjusted in the way you make your heightmap depending on the particular third party software you’re using (ie. World Machine), but I’ve not used any of those really to give you any advice on where to look. If you are using a third party software for your landscape heightmaps perhaps a user here in the community would know off hand what you’d need to adjust to get a smoother result.
I hope this helps!
Tim