Both of mine react exactly the same: In bright light the headlights are in DRL mode and the displays are at their brightest. When the light dims to a certain point the headlights switch to headlight mode, the IP lights come on, and the displays dim. The setpoint for switching to headlights is quite a bit brighter than I like, which is why I had planned to adjust it. In any serious shade, even with bright sun a few feet away it will sometimes switch, and it always switches in my garage, even with the door open.I thought about that too but when the ambient sensor is turned on It operates as it should. The headlights come on at dusk and in sunlight they go off and the DRLs are on. Don't know what the difference is but the DIC is at its brightest when the autolight feature is off.
Have you had the car in direct sun, switched the auto lights on, and seen the display dim?