Operating system: Windows-7-6.1.7601-SP1 64 Bits
Graphics card: GeForce GTX 660 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.20
Broken: version: 2.82 (sub 6), branch: master, commit date: 2020-01-13 17:12, hash: rBc56526d8b68a
Short description of error
The problem: principled BSDF with smallest amount of SSS (higher than 0.00001) still looks almost diffuse but do not give indirect bounces for irradiance volume baking.
Here the file, try to bake.
Exact steps for others to reproduce the error
Set Eevee as render, Add mesh with Principled BSDF, set it`s SSS higher than 0.00001, try to bake irradiance volume probe of indirect lighting from it.