Hi Oldie, the "Müritz" lake is probably mapped correctly. If you click in navigator in place where you would expect the lake, you will see it in info. The reason is that it is mapped twice - once in your relation http://www.openstreetmap.org/relation/2545581 but also in the ways, for example http://www.openstreetmap.org/way/225261915 These duplicities should be filtered out, so it is not expected behavior. hopefully more info later Martin
No - as I said, it is mapped correctly. In OSM it is bit unfortunate, that you can describe objects (lake in this case) with several options. In this case mapping as way and mapping as relation is used, which is from OSM point of view correct (!).
I was last week in holyday nearby and thought I have a look to Müritz in MFN. Another user had meanwhile marked to OSM as well, that the lake in missing in MFN.
So I started a diskussion in the German OSM Forum and they found, that the data have an error there. Somebody is now working on the data. I will check the next MFN map and report here ...