lighting in the scene breaks down with the exact same settings and few added lights. NEED HELP.

hi,

i have this really strange problem here.

this is how my scene looks like:


i added few more lights under the benches, everything is exactly the same and all my lights are static. but this is the result:


what could be wrong with this? the yellow light doesnt produce any GI all of sudden and the whole scene is very dark and low quality.