Map refuses to build lighting..

I’ve taken a screenshot to show the problem. About a second after saying “Kicked Off Swarm”, this error pops up…

Any help would be greatly appreciated!

After many tweaks and variations of possible solutions, I am happy to say that it seemed to be a glitch within the engine or swarm. I have successfully started to build lighting, but I had to copy and paste every single asset over and over about a hundred times in a new project for it to somehow start magically working. Very confusing stuff, but it is finally in the past lol. I will be posting a WIP in the UT forums for my new DM map shortly.