When I rebuilding the lighting, it stays on 99% forever even quality is preview only. Please help!!!
-what do you have in you scene?
-post your pc specs
-open “swarm” (the little yellow swarm icon in the systray) and check if there is still something moving 
The problem is my scene is extremely simple for now, but for some reason won’t work. It works fine b4.
Did you change any value in your baselightmass.ini ? If you did it can explain the render time
Try to drag in LightmassCharacterIndirectDetailVolume and try to rebuild. that worked for me
There is a a little bug with the lightmass volume, make its scale 10,10,10 and build again, it will probably work. 
dunno what i did. but now no problem, hope the same problem won’t comes again especially after I build up a scene. Thank you anyway.