Hi @Thunderloud777 ,
I was researching the issue you’re experiencing, and it seems like it’s been happening since around 2015, as shown in this trend.
I went through several posts and one solution people found was:
“Select all texture samples and set the ‘Sampler Source’ to ‘Shared:Wrap’. in your landscape material’.”
I’m also sharing a video that explains in detail how to paint landscapes using Megascans materials in Unreal Engine 5. It’s a bit old, but it might still be helpful:
How to Paint Landscape with Megascans Materials in Unreal Engine 5
Lastly, here’s the official documentation on Landscape Material Expressions in case you want to go deeper.
https://dev.epicgames.com/documentation/en-us/unreal-engine/landscape-material-expressions-in-unreal-engine?application_version=5.2#landscapelayerblend
Hope it helps and let me know if it worked for you!