Ok, I've figured it out and...this is one of the stranger issues I've yet seen. The problem occurs with a particular material when you enable Global Illumination in this scene. The artwork model on the wall inside the room behind the frosted glass doors is emanating the bluish purple color. The plane has a Paint material applied, with a texture mapped Color. You have the Brightness value of the texture map set at 1.8, which is blowing it out, over-saturating the bounce light from Global Illumination, causing the tint. I set the Brightness value to 1, and all is good. Oddly, this only happens if the material type is set to Paint or Metallic Paint. If changed to any other material type, the tint doesn't occur, even with the higher Brightness value. Perhaps this is a bug (?). I've attached some screen shots.
Eric