My setup is:
Macbook Pro
Unreal 5.1
The scene is lit with Ultra Dynamic Sky
All assets are Nanite, also the foliage (primarily trees).
I appreciate all help on this.
I was getting similar artifacts with lumen and was able to fix with the console commands:
r.Lumen.ScreenProbeGather.ScreenTraces 0
r.Lumen.Reflections.ScreenTraces 0
please be warned, though, I am a newb who just happened to find this fix on a forum and it happened to work for me, however i started having other issues after and i can not say whether or not they are related. you would be wise to create a copy of your file before trying this. hope it helps…