I'm curious is anyone has seen this exception before and had any ideas on resolution.
Basically we periodically create and remove graphics in a GraphicsOverlay, something akin to the following:
MapPoint pt = new MapPoint(lon, lat, elev, SpatialReferences.Wgs84);
pt = GeometryEngine.Project(pt, myMapRefSsytem) as MapPoint;
Graphic g = new PictureMarkerSymbol();