Lighting Build hangs up after Level Streaming added

I have 3 extremely simple levels (just a player and < 5 static meshes total).

When I was working with them as separate levels, lighting builds never took more than 10 seconds each and completed every time.

Today I started streaming two of the levels as sublevels of the other one, and now any lighting build done from the Persistent Level takes <10 seconds to get to 97%, then hangs up / freezes there (I’ve waited 30 minutes without it completing, and no progress shows in Swarm agent).

I’ve found that if I open each sublevel and build those separately, those builds still complete just fine (and very fast, just as before). But even after doing that, when I go back to the persistent level, its build hangs up at 97% within 10 seconds of pressing “Build” (I’ve tried both showing and hiding the rebuilt sublevels when doing the Persistent Level build, it makes no difference).

Given how minimal these levels are, and the fact that they all built just fine before streaming, I’m quite sure it’s not a problem with their complexity (I’ve tried a single lightmass volume for all levels, separate ones on each sublevel, and removing them from all levels – again, makes no difference).

I should note, though, that the level contents overlap in space somewhat – e.g. enabling one level and disabling another swaps in different ground meshes and skyspheres around the player.

Any ideas why adding Level Streaming in this context would cause the Lighting Build to hang up like this?

Hey monotoan,

In order to effectively assist you, I am going to need some simple reproducible steps to get the issue to appear on my end. I was able to find a post that you might find informative when building your lights for the persistent level.

Separate Lighting Between Streamed Levels

Let me know if the post helped you resolve your own issue, or if you have further questions.

Cheers,