Landscape Fractures

Hello, so having an issue while I’ve been building my landscape:

It initially began when after I selected Enable Edit Layers for the Landscape actor (which you can see in the first picture with the lighter green landscape). This Landscape had a 4layer material with relatively minimal adjustments from the base green grass layer. As I fly over the subsection, the nearest quads would resume their shape, but further ones would morph back to flat and fractured.

I was always able to hit “undo”, and it would undo the issue.

However as I progressed, it started agai, so I decided to import a fresh landscape and delete the old one before I got too deep. I used a different Landscape Layer Material that I had downloaded from Brushify and knew was reliable. However the issue began again not too long into the sculpting and isn’t solved by a restart.

Is this a hardware issue? 64x64 vertices with 1135x1135 overall resolution count. The first map was 2x2 subsections and the second was 1x1.

2018 iMac, Mac OS 10.14 Mojave
8 GB internal gpu + 8GB from an eGPU Sonnet Breakaway (whether UE4 can supplement with an eGPU I am not sure)

Same problem on a MacPro 12Core, 8GB Radeon RX580, 24GB Memory, MacOS Mojave.
UE 4.26.2
Maybe a Mac problem?
Landscape fractures when saving the scene and “recoveres” by reloading when switching to landscape mode.

Don´t find any solution…