Lighting building Failed


So there’s the thing, like a lot of people, I got a lighting building error ( I can build it at the begin but after I had 2 or 3 lamp, it still goes ok but at a point it fails), it’s get stuck at 0% and give an error : Lighting build failed. The thing is, when I go offline and try to build, I get : Failed to connect to Swarm. Check that your network interface supports multicast. The funny part is that I’m on mac and I don’t found a way to look in swarn to see what’s happen there. So if anybody could help me ( and I’m pretty pessimist about this given the number of unanswered threads about this ) I would be greatfull. Thanks

Ive never used unreal on a mac but I think on windows that error usually means there was a popup that asked permission for the swarm agent and instead of click OK you clicked Cancel