I have been having a hard time building my light in my persistent level. I check the forums and others have suggested to add lightmass to the exclusion list but the problem still exists. What is weird is if i load each level individually and build the light it works just fine. Now im getting the following error,
I think the problem is that everytime you create a new level, a new instance of UnreaLightMass.exe gets created which needs its own firewall rule. The only solution I can think of is to turn off firewall when working with UE4