You need to find where that flux gate compass is located, because if you store something anywhere near it that might have a magnetic influence upon the compass, then the consequence is exactly what you have experienced. Tools like screwdrivers often have a magnetised tip to the blade, elsewhere in another thread somebody stored an under wired item of clothing next to the flux gate compass, and the compass lost its directional cool. So find the flux gate and make sure nothing is located near enough to create a magnetic influence on it.
As for the fitting of the system, it is most likely that this was done by, or at the request of, the local Bavaria distributor when the boat was new.