Hey Jbgame01,
I didn’t get around to properly being able to test the World Composition Tool as Tim mentioned above if that solves this issue so you should try it and see if it helps. I personally sculpted together a prototype landscape very quickly so I could test a couple things in my game.
It seems to be a problem with Lightmass which compiles the static lighting for the scene. I tried scaling down the landscape and that didn’t help but I did it using the transform on the object which is the final calculation of scale so it’s possible the starting quad sizes were the issue and maybe you have an issue there with Lightmass not being able to compensate for the resolution. I get these holes also on flat surfaces with normals facing upward so I’m sure it’s a possibility.
You can find the documentation on the Landscape Tool here…
And I think if you dig through that, there is a page that has Epic’s recommended sizes to create your terrain from.
But if you are interested in using the World Composition Tool, you can find the documentation here… World Composition in Unreal Engine | Unreal Engine Documentation. And if you let’s use a program like World Machine or an external terrain editor, you could break your image up into tiles for importing in. This may help and Lightmass probably will be able to manage the resolution much better.
And lastly, I ended up not testing because I enabled Distance Field Raytraced Soft Shadows and started going more dynamic but haven’t had the time to address it with Lightmass. So hope this helps you out and also take from me, this is a much better engine than Unity could ever strive to be. Also I believe UE4 is still considered somewhat pre-release so early adopters are bound to have issues.
Hope this helps and good luck.