While playing the game, I found random flickering black thick lines on all the walls. Here are some screenshots and my world settings.
Screenshot-1: Black line is visible here.
Screenshot-2: After sometimes black line will disappear.
The same problem I have in other walls. Screenshot 3 & 4.
I also attached World settings.
I had the exact same problem when I had an object in my scene with 100+ materials on it. I don’t know why it affected my lightmaps that way, but I was able to get rid of it by reducing the amount of materials on that object.
Increase your texture memory pool with this console command :
r.streaming.poolsize 1000 (default), raise it to 2000, 3000 or even higher (equivalent of your gpu vram)