As the title says, I have a level streaming setup containing a few maps that are somewhat close to each other (as they need to be connected). However, it seems that whenever certain levels unload, it also takes a big chunk of the volumetric lightmap in the general vicinity of that map, and it stays gone until the level is loaded back in. This volumetric lightmap data is also still
there on game start, while said map is unloaded- it is only once that map goes through the action of being unloaded (through being entered and then left) that the lightmap data is consumed with it.
Below is a video with volumetric lightmaps visualized, and you can see that they all vanish when unloading a certain unrelated map, also causing nearby dynamic meshes to lose all lighting in the process.
(It also seems that the volumetric lightmap is brighter than lighting once it’s baked- which, is also darker than the original lights in preview dynamic mode. This isn’t the main point of the post however.)
How can I fix this, and ideally make it so the volumetric lightmap data either doesn’t unload, or only unloads with respect of the bounds of other levels?
(Note - I’d rather not use messy or inefficient workarounds that only skirt the issue, like using dynamic lighting in affected rooms, since that doesn’t really fix the main problem, while also hurting performance)