Is Lightmass Importance Volume corrupted in 4.9.1?

I went through the tutorial " Quick Start" level design using version 4.9.1 and found that each time I’ve placed the Lightmass Importance Volume onto my map, my Build Progress Bar always stopped at 88 %. To let you know, this is a very small beginner’s map ( see details below) :

  1. Rotation and Location for the Box Brush are set to zero and scaling at 4,4, 0.1.
  2. The only other light source I have are the default Directional Light and Atmospheric Fog.

That is all- I have no other Actors on the map . I have tried to lower the Lighting Quality from Production to Preview Level prior to initiating the build, but once the build process started, it hangs at 88%. I repeated the above process again, but this time took out the Lightmass Importance Volume, and everything builds completely at 100%.

I’ve decided to duplicate this process using the previous 4.8.3 version and it seems the build process went through without a hitch ( even with the Lightmass Volume scaled to cover the entire area). Does anyone have a similar issue?


Hello Kroka7,

It sounds like your lightmass is building while your light build gets stuck at a certain percentage. This is an issue that we are currently investigating with 4.9. This issue has been finicky while trying to track.

Thank you for reporting this. The ticket number currently associated with this issue is UE - 20782

Thank you very much for reporting this. I would recommend staying in 4.8 for your development while this issue is being resolved. I will keep you up to date with the bugs progress.