I have noticed the same problem, long ago.
The problem is partially in the OSM data, partially in MapFactor Navigator.
In your case, there is a turn restriction "only_straight_on" from the trunk to the primary road, but the "no_left_turn" to the opposite trunk, which would prevent your 'funny' turn, is missing.
http://wiki.openstreetmap.org/wiki/Relation:restriction
I am mapping in OSM only "no_left" and "no_right" restrictions, but not everyone is doing the same.
MapFactor, it seams that "no_..." restrictions are working, but OSM restrictions "only_..." are not taken into account.
Please verify.
Is it possible that Mapfactor will support three segments for U-turn restrictions in the future? I really wouldn't know how to tag u-turns on crossings like this in two segments: http://www.openstreetmap.org/?lat=52.092353&lon=4.331242&zoom=18&layers=M (i'm referring to the primary/secondary crossing there with three no_u_turns)
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