Hello,
I am not sure why, but I keep having issue to build lighting on my maps. The issue happen only when I use the editor version built from the unreal sources from GitHub.
For now, the only way I found to compile the lighting is to open the official version from my Epic Library, then open my project and I can built my lighting, then if I come back to my editor built from sources, everything is fine.
I probably need to build something (not sure what, SwarmAgent seems built already) or configure something. But seeing the number of people having the exact same issue and none of the response working, I guess there is something that everybody miss there.