I am going to take a guess that the problem is one of communication between the various controllers on the car (the roof controller, which manages the light sensor, the central electrical controller, which manages the exterior lights, and the instrument cluster controller, which manages the instrument cluster lights.
So, my suggestion to you is that you have a look at this post TB: Distortion in the Display Unit in the Instrument Cluster (MFI, or Y24), then go to your VW dealer and ask them to check the version number of the software in your instrument cluster (controller 17). If the version number is lower than 21 (meaning, it ends in two digits less than 21, the digit in the 'hundreds' position is not significant), perhaps suggest that the dealership carry out TB 90-05-04 on your car. This will flash-update the instrument cluster software to version 21.
The software updates (there are actually several that will be applied, first it is taken to version 18, then next taken up to version 21) address a number of issues, one of which is occasional disruption in communications between controllers. See if that fixes your problem.
Although this is just an 'educated guess' on my part, it is a reasonably inexpensive action to update this software, and if it solves your problem (which I think it will), it will save all sorts of head-scratching, troubleshooting, taking stuff apart, things like that.