Ok, something interesting (weird) happened when I did the Multipart-to-Singlepart protocol in one of the feature class; the original set geometry type was 'Polygon' for all parcel features but after the Multipart-Singlepart protocol a line feature shows up in the drawing (bus line associated to train stop), not the parcel (polygon) features and geometry type now for all features is 'Polyline M'....
There is another line feature class in the same map, turned off, with the same name....; could that be the problem?