4.18 LPV occlusion broken

Occlusion from LPV seems broken. The light injection works but the occlusion does not. Previous “fix” of disabling DBuffer does not seem to work either. 4.16 works fine, 4.17 “works” with said “fix”, 4.18 is broken. Any work arounds / fixes ?


Are there any steps that I could take to reproduce any issues that are occurring? You could also post screenshots of the problem to have a more clear understanding of it.


Hi. Here’s repo :

Enable r.LightPropagationVolume = 1 in consolevariables.ini

On 4.18 p2

  • Empty level
  • Add atmospheric fog, sky light, directional light, pp volume
  • set lights to movable
  • enable “dynamic indirect lighting” on directional light.
  • set pp volume to unbound, increase lpv size.
  • add some bsp geo/landscape

At this point we can see the LPV injects the light by changing LPV intensity,
but does nothing when you enable occlusion (occlusion intensity 1.0).

On 4.16 occlusion works properly. On 4.17 there is a hinky workaround to disable DBuffer decals which enables the lpv occlusion. No workaround required for 4.16. Problem also affects light injection from point lights apparently. (They dont seem to inject anything).

Exaggerated effect :

Any chance of this getting fixed before 4.18r ?


We were able to reproduce this issue and a JIRA has been created which you can track here: UE-51644


Emission doesn’t seem to be working either, unless dbuffer decals is disabled.

Confirm. Emission materials doesn’t contribute in LPV in 18.1 and 17.2. Any chance to get it fixed ?

Well, emission WAS working in 4.18.0, now it doesn’t work in 4.18.1, I was excited to update my project until this. Epic needs to give LPV some love already.

This issue is majorly hindering the current stage in our project. What gives? What’s the status (other than backlogged)?

Unfortunately, occlusion and emissive injection still aren’t working in 4.20.1.
Is there any chance someone could look into this?

Another “we don’t care” backlogged report.

In my case, in 4.20.1 the emmisive injection in LPV only worked when project setting “Gbuffer decals” was deactivated.