Hello all. So I fired up my projects in Unreal Engine 5.6 today and was shocked how bad it looks. The whole scene was sizzling and flickering. First I blamed lumen but I think it’s my volumes that are broken in UE5.6. I I turn them off the sizzling goes mostly away. But I still have some boiling going on in some scenes that I think is linked to Lumen. Usually I would fix it with:
r.Lumen.ScreenProbeGather.Temporal.DistanceThreshold 0.1
But it doesen’t seem to work in UE5.6
Looking around the community, there have been quite a few instances of this issue. Since 5.6 has just been released, it’s still prone to unexpected behaviours. I would suggest trying the following:
To rule out pre-existing elements on your system, please update your OS to the latest version, and update your video drivers to the Developer version (pick the “Clean Install” option if available)
If you re using Virtual Shadow Maps, disable them, and test with traditional shadows or ray traced shadows instead (do the opposite if your setup’s the other way around)
If Nanite is enabled in your scene, test disabling it
Disable any Ray Tracing effects while working with Lumen
Test switching between DX11 and DX12
If all else fails, roll back to UE 5.5.4 until a hotfix is deployed for 5.6
Thanks, It looks to me that a hotfix is needed. I’m disabling it for now. I also think lumen looks a lot worse in 5.6 when used with a lot of foliage compared to the exact same scene in 5.5.