Windows-10-10.0.16299 64 Bits
GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 419.35
2.80 (sub 50), branch: master, commit date: 2019-03-18 21:39, hash: rBd47f827019f2
Open attached file:
Switch to rendered mode (Eevee). Press 'Bake Indirect Lighting'. You should see dark splotches appear on the wall.
The scene is a room with a window:
There's HDRI map from hdrihaven.com (CC0, 1k). It is rotated so that sun falls inside the room.
There is particle emitter set to render hair as objects:
Walls of the room have a fairly complex material with mixed procedural textures:
When Indirect lighting is baked dark spots appear. They seem to be rather random, each time the pattern is different:
Problem is gone if you remove the emitter. It also helps if you lower number of particles significantly:
Problem is gone when material on the wall is replaced with a simple shader like diffuse or principled: