Fix Disappearing Shadows in UE5.X

 This is likely something you've come across, researched and found the solutions to without too much effort but thought I'd post my findings anyway. Thanks to William Faucher (as usual, he has the solutions to most things) and even Google's basic AI summary when searching for the solutions.

There are 2 parts to this problem. One regarding basic mesh objects and another regarding the same issue but with foliage/instances. I've run into both and they're solved (mostly) with a basic console command.

At it's core, the engine is trying to optimize things and shadows on meshes tend to vanish as the object approaches about 0.02% screen size (in my tests). I didn't want this as it effects my Cinematic scene. Note, I am using the Cinematic scalability settings. 

Using the console command: "r.RayTracing.Culling 0"  keeps the ray trace shadows from culling, regardless of distance.

For foliage, the console command is: "r.Raytracing.Geometry.InstancedStaticMeshes.Culling 0".

Another factor that may play a role in your disappearing shadows could be on the light source's "Dynamic Shadow Distance" setting  as shown above. You may need to increase this depending on the size of your scene and how far away your objects get. 

Obviously there are many other factors that could be affecting your scene if you have this problem, but these seems to be the basic and most common solutions and worked for me.

Good Luck!

Ray traced Shadows and 2 Sided Foliage Shader (follow up)

 I did a little testing (finally) regarding earlier issues I have posted about using Ray Traced Shadows and lighting in UE5.X with foliage and the 2 Sided Foliage shader. Having reported earlier that the issue was fixed I can now say that is indeed true based on my own tests. Granted, there are myriad issues and settings now when enabling ray tracing in your scenes that could effect this, but at it's most basic, sub-surface effects used by the 2 Sided Foliage shader do function when using raytracing in Unreal. 

Obviously, certain settings may affect this, but overall, choosing a base project at the start with Ray Tracing enabled will show sub-surface effects with the shader as shown below:

Project settings with Ray Tracing enabled. I have changed Ray Lighting Mode to HLR and left Lumen as the method for GI and Reflections

Enabling "Ray Traced Shadows" in the Hardware Ray Tracing section of the Project Settings does not affect this dramatically, though the look may be a little different (less intense). Sub Surface properties in the shader still work: