I’m working on a project which generates a giant procedural maze, with about 120,000 instanced static meshes. The meshes no longer generate shadows now that there are so many, I might have to just redo the maze so it generates with multiple separate actors with less instances each but I would really prefer some solution to render shadows on this one actor with a ton of instances, thanks!
Are you using a stationary or dynamic light?
Also, you may want to look at this: [Editor Feature Pull Request] Rama's Instanced Static Mesh Editor Feature - Engine Source & GitHub - Unreal Engine Forums
Not sure if it lets you generate it ingame like that, but you may be able to modify what he did to get it working.