Well, your setting look quite alright actually (Only that I would personally use EXR with Anti-Aliasing cranked up)
I would have a hard time to help further without seeing the scene unfortunately. Its a troubleshoot problem that need to get by elimination mostly.
My biggest issue would be the post process that doesn’t take all the meshes in consideration - this never happened to me.
I will follow the thread tho because I’m curious if somebody have an answer to that.
If you want to share your project so I can take a look, feel free to reach directly - it might be easier.
To tweak nanites, you can play with those setting inside your Static Mesh editor
