Multiple sublevel lighting breaks

Hello,

I have multiple bigger scenes that I want to load and unload during gameplay. This is a VR project with some (2) apartment scenes by Evermotion. I prepared them and split them into many sublevels that I want to stream into my Persistent Level that just has the player. I am using UE 4.18.3.

I’ve read a lot about troubleshooting regarding sublevel lighting already, but I still have one problem: For a single apartment scene all my lights are in one sublevel, I have another for reflection captures and a couple others for static meshes. I can make all sublevels of one apartment scene visible and build the light. Then I can go do the same for the other apartment scene, so far so good. But if I go back to my first apartment scene the light is broke. Not the actual light maps themselves (“Lighting Only” shows light maps just fine), but something.

What is interesting is that I can start the light build, cancel it and the scene looks fine.

Lighting build is broke after switching and building sublevels of other scene ^

Start and cancel light build and light is fixed ^

The same is happening for the other apartment scene ^

After a couple times of trying this out, at some point both scenes work now. But I have to make changes to this and add another scene. It will be broke in no time again. I would like to know what the cause for it sometimes working is. The message when doing the bake here also says “Leaving them hidden may invalidate what is built on other levels.”, which is probably what is happening. v

I’ve read of another method here: Lighting scenarios affect other sublevels - Rendering - Epic Developer Community Forums where the solution is to bake the sublevels and then load them into the persistent level. Unfortunately I haven’t been able to load a map consisting out of sublevels to show up in the persistent map. I need to have the apartment scenes split into multiple sublevels too, because otherwise I can not package the project (2GB size limit for maps). In the screenshot below you can see how I’m loading two maps containing the sublevels of the apartment scenes, but the only thing that shows up are the actors (player) of the actual level (their “persistent” map) and not the sublevels that are in them. What am I doing wrong here?

The two levels containing many sublevels loaded into a new, empty level ^

Would be great if somebody had some advice!
Thank you and have a nice day.