Recently migrated a project from 4.24 to 4.25 and for some reason the camera lens grain stopped working. I tried recompiling shaders, enabling or disabling mobile HDR, tone mapper and selecting different rendering preview levels but no luck. It only works on SM5.
I believe it’s a bug since it works when using 4.24.
Curious if you ever got this figured out? I am also experiencing this problem and wondering what the solution is? The documentation has it listed as supported: Supported Rendering Features | Unreal Engine Documentation
There’s no workaround sadly, but they’re tracking the issue on: Unreal Engine Issues and Bug Tracker (UE-96732)
I managed to create a custom post process filter to simulate something similar but it’s not quite there yet.