In 4.14 when entering the volume the screen brightens which is expected.
The problem is that in 4.15 it brightens more. So much so that some static meshes are rendered almost completely white.
I tested this on an R9 380, and was also able to reproduce on a Quadro M6000, and a GTX 980.
Expected Result: The viewport brightens
Actual Result: The viewport brightens too much
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-40127 in the post.