hello , I build light on my project , it stop 99% and swarm doesn’t move.
but my CPU and RAM processing
*** my swarm status ***
*** my swarm Log ***
anyone can help me please 
unreal 4.12.5
It’s still rendering, just let it keep going
It can get slower to the end because each object gets sent to a single thread so you can end up with one thread still working on an object because the other threads can’t contribute to it.
As I can say based on our experience, this is normal, unfortunately.
Every big build here takes hours: the light building goes quite fast and well until it reaches about 99.95%, then it slows down for hours and hours with only one computer working on it.
Quite frustrating, but I suppose this is the actual behaviour.
Thank you very much, darthviper107 and berna 